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Foundations of Math II Unit 4: Trigonometry Academics High School Mathematics

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Page 1: fomii unit 4 student packet 10.17.2013...2. Find BC 1. Mark angle with the given value. 2. Label the sides in relation to the given angle (opp, adj, hyp) 3. Circle the known relationships

Foundations  of  Math  II  

Unit  4:  Trigonometry    

 

 

 

 

 

 

 

 

 

     

 

Academics    High  School  Mathematics  

Page 2: fomii unit 4 student packet 10.17.2013...2. Find BC 1. Mark angle with the given value. 2. Label the sides in relation to the given angle (opp, adj, hyp) 3. Circle the known relationships

2    

4.1  Warm  Up    1) a) Accurately draw a ramp which forms a 14° angle with the ground, using the grid below.

b) Find the height of a support board which could be used to make your ramp, and the distance of the support board from the beginning of your ramp.

c) Draw another ramp which forms a 14° angle with the ground, and give its measurements as in part (b).

d) What do you notice?

                                         Adapted  from  Geometry:  A  Moving  Experience  developed  by  the  Curriculum  Research  &  Development  Group,  College  of  Education  at  the  University  of  Hawaii  

Page 3: fomii unit 4 student packet 10.17.2013...2. Find BC 1. Mark angle with the given value. 2. Label the sides in relation to the given angle (opp, adj, hyp) 3. Circle the known relationships

3    

4.1 Lesson Handout

1. Jill is building a ramp. She knows that she must place the support board 142 in. from the base of the

ramp. The ramp must make a 22° angle with the ground. She needs to figure out how high to make the support board. Jill draws a picture of the situation and asks Bill to help her solve for q in the triangle shown. Bill says, “If you tell me the slope of a 22°  line, a line which forms a 22° angle with the x-axis, I can tell you what q is.”

 

a) Help Jill accurately find the slope of a 22° line.

b) How will Bill find q?

c) Repeat parts (a) and (b) if ∠A = 44°.

Adapted  from  Geometry:  A  Moving  Experience  developed  by  the  Curriculum  Research  &  Development  Group,  College  of  Education  at  the  University  of  Hawaii  

B

142

q

22° A C

Page 4: fomii unit 4 student packet 10.17.2013...2. Find BC 1. Mark angle with the given value. 2. Label the sides in relation to the given angle (opp, adj, hyp) 3. Circle the known relationships

4    

4.1 Practice

Now Jill wants to build another ramp. This time the ramp must make a 40° angle with the ground and she has a support board that is 10 in. high. She needs to know how far from the base of the ramp to place the support board. Jill draws a picture of the situation and asks Bill to help her solve for x in the triangle shown below, which is not drawn to scale. Bill says, “If you tell me the slope of a 40°  line, I can tell you what x is.”

 

a) Help Jill accurately find the slope of a 40° line. b) How will Bill now find x? Find x. c) Repeat parts (a) and (b) if ∠A = 62°. d) Repeat parts (a) and (b) if ∠A = 9°. e) Repeat parts (a) and (b) if ∠A = 22° f) Bill says, “This is fun! Let’s do a few more!” Jill says, “I am getting tired of all this work, Bill. There

must be an easier way to find slopes.” What do you think?

Adapted  from  Geometry:  A  Moving  Experience  developed  by  the  Curriculum  Research  &  Development  Group,  College  of  Education  at  the  University  of  Hawaii  

x

10 in.

40° A

B

C

Page 5: fomii unit 4 student packet 10.17.2013...2. Find BC 1. Mark angle with the given value. 2. Label the sides in relation to the given angle (opp, adj, hyp) 3. Circle the known relationships

5    

4.2 Practice Tangent Ratio 1) Find tan A

a) Mark ∡𝐴. b) What is the length of the support board (opposite side)? c) What is the length of the ramp (hypotenuse)? d) What is the distance from the support board to the base of the

ramp (adjacent side)? e) Write the tangent ratio for ∡𝐴. f) Change the ratio to decimal form. Use the table to find the value

of ∡𝐴. 2) Find tan B.

a) Redraw �𝐴𝐵𝐶 so that 𝐵𝐶 is the base of the ramp and 𝐴𝐶 is the support board. Mark ∡𝐵.

b) What is the length of the support board (opposite side)? c) What is the length of the ramp (hypotenuse)? d) What is the distance from the support board to the base of the

ramp (adjacent side)? e) Write the tangent ratio for ∡𝐵. f) Change the ratio to decimal form. Use the table to find the value

of ∢𝐵. How else can you find the measure of ∡𝐵? 3) Find the missing measurements in each triangle below. All measurements are given in centimeters.

4) Jill says to Bill, “I know the answer to this one without having to write anything down.” What do you

think Jill means?

A C

5  

12  

13  B

Page 6: fomii unit 4 student packet 10.17.2013...2. Find BC 1. Mark angle with the given value. 2. Label the sides in relation to the given angle (opp, adj, hyp) 3. Circle the known relationships

6    

4.2 Homework Tangent Ratio

1) Find tan N a) Mark ∡𝑁.

b) What is the length of the support board (opposite side)?

c) What is the length of the ramp (hypotenuse)? (Hint: Use the Pythagorean Theorem.)

d) What is the distance from the support board to the base of the ramp (adjacent side)?

e) Write the tangent ratio for ∡𝑁.

f) Change the ratio to decimal form. Use the table to find the value of ∡𝑁.

2) Find tan M.

a) Redraw �𝑀𝑁𝑃 so that 𝑀𝑃 is the base of the ramp and 𝑁𝑃 is the support board. Mark ∡𝑀.

b) What is the length of the support board (opposite side)?

c) What is the length of the ramp (hypotenuse)?

d) What is the distance from the support board to the base of the ramp (adjacent side)?

e) Write the tangent ratio for ∡𝑀.

f) Change the ratio to decimal form. Use the table to find the measure of ∡𝑀. How else can you find the value of ∡𝑀?

 

3) DM = ________

4) TR = ________

AT = _________

m∠T=________

5) x ≈_______

y ≈_______

6) q =______

y =______

x

7 40°   y

q

20

28°

y

Page 7: fomii unit 4 student packet 10.17.2013...2. Find BC 1. Mark angle with the given value. 2. Label the sides in relation to the given angle (opp, adj, hyp) 3. Circle the known relationships

7    

4.3 Applications of the Tangent Ratio Lesson Handout

Example 1 Jenna goes on an exciting airplane ride. She takes off at a 25° angle and continues flying in a perfectly straight path until she is directly over her house, as shown. She notices that her altitude when directly over her house is 3,200 feet. What distance has she flown?

Example 2 Carl decides to use what he has learned about trigonometry to help him find the height of his favorite tree. At a certain time of day, he measures the tree’s shadow with a tape measure and finds that it is 31 feet long. Then he measures the angle of elevation to the sun using a clinometer and finds that the sun’s rays are striking at a 62° angle with the ground. (The angle that the sun’s rays make as they strike an object determines the length of the object’s shadow.) Use the information and what you know about trigonometry to calculate the height of the tree.

 

 

 

 

Page 8: fomii unit 4 student packet 10.17.2013...2. Find BC 1. Mark angle with the given value. 2. Label the sides in relation to the given angle (opp, adj, hyp) 3. Circle the known relationships

8    

Example 3 Erica is standing on one side of a canyon, and her friend Sasha is standing directly across the canyon from her on the other side. They want to know how wide the canyon is. Erica marks her spot and then walks 10 yards along the canyon edge and looks back at Sasha. The angle of her line of sight to Sasha and the path she just walked is 72°. Draw a sketch that illustrates this situation. What is the approximate width of the canyon?

Example 4

Page 9: fomii unit 4 student packet 10.17.2013...2. Find BC 1. Mark angle with the given value. 2. Label the sides in relation to the given angle (opp, adj, hyp) 3. Circle the known relationships

9    

4.3 Applications of the Tangent Ratio Practice

2) To see the top of a building 1000 feet away, you look up 28° from the horizontal. What is the height of the building?

3) A guy wire is anchored 12 feet from the base of a pole. The wire makes a 62° angle with the ground. How long is the wire?

4) An evergreen tree is supported by a wire extending from 1.5 feet below the top of the tree to a stake in the ground that is 15 feet from the base of the tree. The wire forms a 58° angle with the ground. How tall is the tree?

1)

   

Page 10: fomii unit 4 student packet 10.17.2013...2. Find BC 1. Mark angle with the given value. 2. Label the sides in relation to the given angle (opp, adj, hyp) 3. Circle the known relationships

10    

4.3 Applications of the Tangent Ratio Homework

1) To the nearest tenth of a foot, how tall is a building 100 feet away (d = 100) if the top of the building is sighted at a 20° angle (n = 20°)?

2) If an object is dropped from the top of the leaning tower of Pisa, it will land about 13 feet from the base of the tower. The tower leans at an angle of approximately 86°. How far did the object drop?

3) A ramp was built by the loading dock of a building. The height of the loading dock platform is 7 feet. Determine the length of the ramp if it makes a 38° angle with the ground. (Draw a picture!)

4) A jet airplane begins a steady climb of 15˚ and flies for two ground miles. What was its change in altitude?

86°

d

13 ft.

Page 11: fomii unit 4 student packet 10.17.2013...2. Find BC 1. Mark angle with the given value. 2. Label the sides in relation to the given angle (opp, adj, hyp) 3. Circle the known relationships

11    

4.4  Warm  Up    1)  Jenna  goes  on  another  exciting  airplane  ride.    She  takes  off  at  a  35°  angle  and  continues  

flying  in  a  perfectly  straight  path  for  five  miles.    She  discovers  that  she  is  directly  over  her  house.      

 

 

 

 

 

a) How  far  is  her  house  from  the  airport?  b) What  is  her  altitude?    

                                   

Adapted  from  Geometry:  A  Moving  Experience  developed  by  the  Curriculum  Research  &  Development  Group,  College  of  Education  at  the  University  of  Hawaii  

35°  

5  mi  

Page 12: fomii unit 4 student packet 10.17.2013...2. Find BC 1. Mark angle with the given value. 2. Label the sides in relation to the given angle (opp, adj, hyp) 3. Circle the known relationships

12    

4.4  Trigonometric  Ratios  Lesson  Handout    

The  word  trigonometry  comes  from  2  Greek  words,  trigon,  meaning  triangle,  and  metron,  meaning  measure.    The  study  of  trigonometry  involves  triangle  measurement.      

We  will  be  studying  basic  _________________          ____________________        _______________________  

Identifying  Sides          

 

Hypotenuse  side  ___________              

Opposite  of  angle  A  _________          Opposite  of  angle  B________  

Adjacent  to  Angle  A  _________        Adjacent  to  Angle  B  _______  

 

The  trig  ratios  we  will  be  studying  are  ________________,  __________________,  and  ______________________  

The  ratios  for  each  function:      

Sin  =___________________                Cos  =  ____________________            Tan  =  ____________________  

Setting  up  Ratios  

         

Sin  A  =  __________     Sin  B  =  _________  

        Cos  A  =  __________     Cos  B  =  _________  

        Tan  A  =  __________     Tan  B  =  _________  

 

 

        Sin  X  =  __________     Sin  Y  =  _________  

        Cos  X  =  __________     Cos  Y  =  _________  

        Tan  X  =  __________     Tan  Y  =  _________  

 

 

A  

b  

a  C   B  

c  

A  

3  

4  C   B  

5  

13  

X  

12  

5   Y  Z  

Page 13: fomii unit 4 student packet 10.17.2013...2. Find BC 1. Mark angle with the given value. 2. Label the sides in relation to the given angle (opp, adj, hyp) 3. Circle the known relationships

13    

Using  a  Calculator  

Sin  39  =  _________   Cos  58  =  _________           Tan  85  =  _________   Sin  30  =  _________  

 

 

Solving  for  a  Side  

1.           2.  

 

 

 

 

 

 

3.               4.      

   

 

 

X      

10  

38°  

 

45  

     

A  

50°  

 

34  

 

 

 z  70°  

 Y  

12  

   

 85°  

Page 14: fomii unit 4 student packet 10.17.2013...2. Find BC 1. Mark angle with the given value. 2. Label the sides in relation to the given angle (opp, adj, hyp) 3. Circle the known relationships

14    

4.4  Trigonometric  Ratios  Practice  

1. Find sin A.

1. Mark ∡𝐴. 2. Label the sides in relation to ∡𝐴 (opp, adj, hyp) 3. Circle the sides that are needed to find sin (opp, hyp) 4. Write the sin ratio for ∡𝐴 5. Change the ratio to decimal form.

Sin A = _________

2. Find BC

1. Mark angle with the given value. 2. Label the sides in relation to the given angle (opp, adj, hyp) 3. Circle the known relationships. (adj, hyp) 4. Decide which trig function uses these two relationships. 5. Write the trig equation used to solve this problem. 6. Solve the equation.

BC = _________

3. Find the measure of each side indicated. Round your answer to the nearest tenth.

a. b.

4. Suppose you’re flying a kite, and it gets caught at the top of the tree. You’ve let out all 100 feet of string for the kite, and the angle that the string makes with the ground is 75 degrees. Instead of worrying about how to get your kite back, you wonder. “How tall is that tree?”

A

B

C

5  

12  

13  

A C

x  17  

B

50°  

100  ft  

75°  

h  

Page 15: fomii unit 4 student packet 10.17.2013...2. Find BC 1. Mark angle with the given value. 2. Label the sides in relation to the given angle (opp, adj, hyp) 3. Circle the known relationships

15    

4.4 Trigonometric  Ratios  Homework  

1. Find each of the trig ratios for the triangle at the right:

sin A = sin B =

cos A = cos B =

tan A = tan B =

2. Find the measure of each side indicated. Round to the nearest tenth.

a. b.

c. d.

3. Solve the following triangles. Round your answer to the nearest tenth.

a. b.

5

x

y

50

36

8x

y

z°   z°  

Page 16: fomii unit 4 student packet 10.17.2013...2. Find BC 1. Mark angle with the given value. 2. Label the sides in relation to the given angle (opp, adj, hyp) 3. Circle the known relationships

16    

4. You are in charge of ordering a new rope for the flagpole. The rope needs to be twice the height of the flagpole. To find out what length of rope is needed, you observe that the pole casts a shadow 12 meters long on the ground. The angle between the sun’s rays and the ground is 37°. How tall is the pole? How much rope do you need?

5. A damsel is in distress and is being held captive in a tower. Her knight in shining armor is on the

ground below with a ladder. The knight leans the ladder against the tower. When the knight stands 15 feet from the base of the tower and looks up at his precious damsel, the angle between the ladder and the ground is 60°. How long does the ladder have to be in order to reach the window?

 

6. The tailgate of a moving van is 3.5 feet above the ground. A loading ramp is attached to the rear of the van. The angle that the ramp makes with the ground is 10°. Find the length of the loading ramp to the nearest tenth of a foot.

12  m    37°    

h  

   

Page 17: fomii unit 4 student packet 10.17.2013...2. Find BC 1. Mark angle with the given value. 2. Label the sides in relation to the given angle (opp, adj, hyp) 3. Circle the known relationships

17    

4.5 Warm Up 1) Find the measure of ∡𝑇 and ∡𝐺

 

 

 

 

                                                           Adapted  from  Geometry:  A  Moving  Experience  developed  by  the  Curriculum  Research  &  Development  Group,  College  of  Education  at  the  University  of  Hawaii  

R  

G  

T  

4  3  

Page 18: fomii unit 4 student packet 10.17.2013...2. Find BC 1. Mark angle with the given value. 2. Label the sides in relation to the given angle (opp, adj, hyp) 3. Circle the known relationships

18    

4.5    Inverse  Trigonometric  Ratios  Practice    1. Find each angle measure to the nearest degree

a. tan A = 2.0503 b. cos Z = 0.1219

c. sin U = 0.8746

2. Find the measure of the indicated angle to the nearest degree.

a. b.

c. d.

Page 19: fomii unit 4 student packet 10.17.2013...2. Find BC 1. Mark angle with the given value. 2. Label the sides in relation to the given angle (opp, adj, hyp) 3. Circle the known relationships

19    

4.5 Inverse  Trigonometric  Ratios  Homework    1. Find each angle measure to the nearest degree

a. tan Y = 0.6494 b. cos V = 0.6820

c. sin C = 0.2756

2. Find the measure of the indicated angle to the nearest degree.

a. b.

c. d.

3. Solve each triangle. Round answers to the nearest tenth.

a. b.

7

10

13

26

Page 20: fomii unit 4 student packet 10.17.2013...2. Find BC 1. Mark angle with the given value. 2. Label the sides in relation to the given angle (opp, adj, hyp) 3. Circle the known relationships

20    

4.6  Warm  Up  

1) Jill attaches a rope to the Wilderness Survival Training Program tower, 60 feet above the ground. Her rope is 90 feet from the base of the tower and forms a 34° angle with the ground, as shown below. Bill wants to attach a rope to the tower so that the angle it forms with the ground is twice as large as that of Jill’s rope. If Bill’s rope is also 90 feet from the base of the tower, how far above the ground should Bill attach his rope? Explain your answer.

 

                     

 

Adapted  from  Geometry:  A  Moving  Experience  developed  by  the  Curriculum  Research  &  Development  Group,  College  of  Education  at  the  University  of  Hawaii  

34°  

60  feet  

Page 21: fomii unit 4 student packet 10.17.2013...2. Find BC 1. Mark angle with the given value. 2. Label the sides in relation to the given angle (opp, adj, hyp) 3. Circle the known relationships

21    

4.6  Applications  –  Find  the  Missing  Angle  Practice    

1. Two legs of a right triangle are 16 and 48. Find the measure hypotenuse and all the angles.

2. One leg of a right triangle is 14 while the hypotenuse is 38. Find the measure of the other leg and all the angles.

3. The bottom of 24-foot ladder is 6 feet from the building that the ladder is leaning against. In order for the ladder to be set-up safely the angle the ladder makes with the ground cannot exceed 75°. Is the ladder set up safely? How do you know?

4. A jet airplane out of Denver, Colorado needs to clear a 1,500 ft mountain 1 mile (5,280 feet) after it takes off. If the plane makes a steady climb after takeoff, what angle does the plane need to take to clear the mountain?

5. The Washington Monument is 555 feet tall. An observer is 300 feet from the base of the monument. If the observer is lying on the ground looking to the top of the monument, find the angle made between the observer’s line of sight and the ground.

Page 22: fomii unit 4 student packet 10.17.2013...2. Find BC 1. Mark angle with the given value. 2. Label the sides in relation to the given angle (opp, adj, hyp) 3. Circle the known relationships

22    

4.6  Applications  –  Find  the  Missing  Angle  Homework    

1. One leg of a right triangle is 10 while the hypotenuse is 27. Find the measure of the other leg and all the angles.

2. A road rises 10 feet for every 400 feet along the pavement (not the horizontal). What is the measurement of the angle the road forms with the horizontal?

3. A 32-foot ladder leaning against a building touches the side of the building 26 feet above the ground. What is the measurement of the angle formed by the ladder and the ground?

4. A wire anchored to the ground braces a 17-foot pole. The wire is 20 feet long and is attached to the pole 2 feet from the top of the pole. What angle does the wire make with the ground?

5. Margo is flying a kite at the park and realizes that all 500 feet of string are out. She has staked the kite in the ground. If she knows that the kite is 338 feet high, what is the angle that the kite makes with the ground?

   

Page 23: fomii unit 4 student packet 10.17.2013...2. Find BC 1. Mark angle with the given value. 2. Label the sides in relation to the given angle (opp, adj, hyp) 3. Circle the known relationships

23    

4.7  Angles  of  Elevation  and  Depression  Practice  

1 At a certain time of day the angle of elevation of the sun is 44°. Find the length of the shadow cast by a building 30 meters high.

2 The top of a lighthouse is 120 meters above sea level. The angle of depression from the top of the lighthouse to the ship is 23°. How far is the ship from the foot of the lighthouse?

3 A lighthouse is 100 feet tall. The angle of depression from the top of the lighthouse to one boat is 24°. The angle of depression to another boat is 31°. How far apart are the boats?

4. At a point on the ground 100 ft. from the foot of a flagpole, the angle of elevation of the top of the pole contains a 31 degree angle. Find the height of the flagpole to the nearest foot.

5. From the top of a lighthouse 190 ft. high, the angle of depression of a boat out at sea is 34 degrees. Find to the nearest foot, the distance from the boat to the foot of the lighthouse.

6.    Find to the nearest degree the measure of the angle of elevation of the sun if a post 5 ft. high casts a shadow 10 ft. long.  

Page 24: fomii unit 4 student packet 10.17.2013...2. Find BC 1. Mark angle with the given value. 2. Label the sides in relation to the given angle (opp, adj, hyp) 3. Circle the known relationships

24    

4.7  Angles  of  Elevation  and  Depression  Homework  

Draw  a  picture,  write  a  trig  ratio  equation,  rewrite  the  equation  so  that  it  is  calculator  ready  and  then  solve  each  problem.    Round  measures  of  segments  to  the  nearest  tenth  and  measures  of  angles  to  the  nearest  degree.  

________1.    A  20-­‐foot  ladder  leans  against  a  wall  so  that  the  base  of  the  ladder  is  8  feet  from  the  base  of  the  building.    What  is  the  ladder’s  angle  of  elevation?  

 

 

 

 

________2.    A  50-­‐meter  vertical  tower  is  braced  with  a  cable  secured  at  the  top  of  the  tower  and  tied  30  meters  from  the  base.    What  is  the  angle  of  depression  from  the  top  of  the  tower  to  the  point  on  the  ground  where  the  cable  is  tied?  

________3.    At  a  point  on  the  ground  50  feet  from  the  foot  of  a  tree,  the  angle  of  elevation  to  the  top  of  the  tree  is  53°.    Find  the  height  of  the  tree.  

 

 

 

 

 

________4.    From  the  top  of  a  lighthouse  210  feet  high,  the  angle  of  depression  of  a  boat  is  27°.    Find  the  distance  from  the  boat  to  the  foot  of  the  lighthouse.    The  lighthouse  was  built  at  sea  level.  

________5.    Richard  is  flying  a  kite.    The  kite  string  has  an  angle  of  elevation  of  57°.    If  Richard  is  standing  100  feet  from  the  point  on  the  ground  directly  below  the  kite,  find  the  length  of  the  kite  string.  

 

 

 

 

 

________6.    An  airplane  rises  vertically  1000  feet  over  a  horizontal  distance  of  5280  feet.    What  is  the  angle  of  elevation  of  the  airplane’s  path?  

   

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Making a Clinometer Equipment You will need: • A clinometer template cut out of card stock. • Some sticky tape. • A straw. This needs to be straight enough that you can see all the way through. You may need to snip off any ‘bendy bits’. • Some thread. • A washer. Instructions 1. Cut out the card along the dashed lines 2. Cut a length of thread (about 15cm) 3. Tape the thread so that it hangs along the zero line. Make sure that it pivots at the crosshairs.

4. Tie a washer on the end of the thread to make a plumb line. 5. Tape a drinking straw parallel to the 90° line. It should be as close as possible and must not interfere with the plumb line. 6. Your clinometer is ready to use.

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Clinometer Lab

In this lab, you will create and use a clinometer. A clinometer is an instrument that measures the angle between the ground or the observer and a tall object, such as a tree or a building.

 

To be Completed Inside:

1. Decide the roles:

PARTNER A : the Pacer:________________________________ PARTNER B: the Clinometer Person:____________________________

2. Get 2 lengths using a ruler, meter stick, or tape measure:

Partner A’s (The pacer’s) foot length: ____________ meters

Partner B’s (The Clinometer person’s) height from floor to eyes: ____________ meters

3. Make a clinometer

4. Practice using the Clinometer.

a. Look straight ahead at an object in the room (keep the Clinometer horizontal).

i.What angle of elevation should this be? _____________

ii.What angle does the Clinometer give you? _____________

Name: _________________________ Period: ____ Date: _________

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b. Look straight up at the ceiling (make the Clinometer perfectly vertical).

i.What angle of elevation should this be? _____________

ii. What angle does the Clinometer give you?____________

5. Use the Clinometer to find the height of the wall in our classroom.

STEPS:

1. Partner A, use your foot length to pace out and measure the distance from Partner B to the wall.

2. Partner B, use the Clinometer to get the angle. 3. Write in numbers for the 3 ‘?’ marks. 4. Use trig to find the height of the wall.

** (don’t forget to add Partner B’s height) **

To be completed outside:

Name  of  Object  Measured   Clinometer  Angle   Number  of  Foot  lengths  to  base  of  building  

Calculated  distance  from  base  of  building  (meters)  

       

       

       

       

       

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Your  mission  is  to  use  your  data  and  a  little  trigonometry  to  find  the  height  of  each  of  the  five  objects  you  chose.    

Draw  AND  label  a  picture.  Show  all  of  your  work/calculations.      

1.  Calculated  Height__________________  

 

 

 

 

                 

 

 

 

2.  Calculated  Height__________________  

 

 

 

 

 

 

 

 

3.  Calculated  Height__________________  

 

 

 

 

 

 

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4.  Calculated  Height__________________  

 

 

 

 

 

 

 

 

 

5.  Calculated  Height__________________  

 

 

 

 

 

 

 

 

Summarize  

Write  out  the  step-­‐by-­‐step  process  you  used  to  calculate  the  height  of  your  objects.    (Just  look  at  you  picture  and  work  and  state  what  you  did  first,  then  what  you  did  next,  etc).    Continue  your  summary  on  the  back  of  this  paper  if  you  need  more  room.    

           

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4.8  Homework  ________7.    A  person  at  one  end  of  a  230-­‐foot  bridge  spots  the  river’s  edge  directly  below  the  opposite  end  of  the  bridge  and  finds  the  angle  of  depression  to  be  57°.    How  far  below  the  bridge  is  the  river?  

 

 

 

________8.    The  angle  of  elevation  from  a  car  to  a  tower  is  32°.    The  tower  is  150  ft.  tall.    How  far  is  the  car  from  the  tower?  

________9.    A  radio  tower  200  ft.  high  casts  a  shadow  75  ft.  long.    What  is  the  angle  of  elevation  of  the  sun?  

 

 

 

 

 

 

________10.    An  escalator  from  the  ground  floor  to  the  second  floor  of  a  department  store  is  110  ft  long  and  rises  32  ft.  vertically.    What  is  the  escalator’s  angle  of  elevation?  

________11.    A  rescue  team  1000  ft.  away  from  the  base  of  a  vertical  cliff  measures  the  angle  of  elevation  to  the  top  of  the  cliff  to  be  70°.    A  climber  is  stranded  on  a  ledge.    The  angle  of  elevation  from  the  rescue  team  to  the  ledge  is  55°.    How  far  is  the  stranded  climber  from  the  top  of  the  cliff?    (Hint:    Find  y  and  w  using  trig  ratios.    Then  subtract  w  from  y  to  find  x)  

 

 

 

 

 

 

________12.    A  ladder  on  a  fire  truck  has  its  base  8  ft.  above  the  ground.    The  maximum  length  of  the  ladder  is  100  ft.    If  the  ladder’s  greatest  angle  of  elevation  possible  is  70°,  what  is  the  highest  above  the  ground  that  it  can  reach?  

   

   230  

110    32  

1000  

x  

w  y  

8  

100  

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4.9  Warm  Up    

Archeologists  have  recently  started  uncovering  remains  of  Jamestown  Fort  in  Virginia.    The  fort  was  in  the  shape  of  an  isosceles  triangle.    Unfortunately,  one  corner  has  disappeared  into  the  James  River.    If  the  remaining  complete  wall  measures  300  feet  and  the  remaining  corners  measure  46.5°  and  87°,  what  was  the  approximate  area  of  the  original  fort?    How  long  were  the  two  incomplete  walls?  

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Adapted  from  Discovering  Geometry:  An  Investigative  Approach,  Key  Curriculum  Press  ©2008    

Page 32: fomii unit 4 student packet 10.17.2013...2. Find BC 1. Mark angle with the given value. 2. Label the sides in relation to the given angle (opp, adj, hyp) 3. Circle the known relationships

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4.9  Area  of  a  Triangle  Practice    Find the area of each triangle below.  1. 2.

 

 

3. 4.

5. A new homeowner has a triangular-shaped back yard. Two of the three sides measure 53 ft and 42 ft and form an included angle of 135°. To determine the amount of fertilizer and grass seed to be purchased, the owner has to know, or at least approximate, the area of the yard. Find the area of the yard to the nearest square foot.

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4.9  Area  of  a  Triangle  Homework    Using your knowledge of area of a triangle, right triangle trigonometry, and the Pythagorean Theorem, find the area of each triangle below. Round your final answer to one decimal place.

1. 2.

3. 4.

5. The intersection sof three roads lea\ves a traingular piece of ground in the middle. What is the area of the grassy section?

6. The area of a triangle is 38 square centimeters. AB is 9 centimeters and BC is 14 centimeters. Calculate the size of the acute angle ABC.

 

 

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4.10  Warm  Up    Find  the  area  of  the  following  triangle.              

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4.10  Law  of  Sines  Practice    Solve for the unknown in each triangle. Watch out for the ambiguous case.

1. 2. 3. 4. 5. 6. 7. Suppose that you are the pilot of a commercial airliner. You find it necessary to detour around a group of thundershowers. You turn at an angle of 21 degrees to your original path, fly for a while, turn, and intercept your original path at an angle of 35 degrees, 70 km from where you left it.

How much further did you travel as a result of the detour? What is the area of the triangle?

   

x  

42°  

22m  

17m   x  35°  

44mm  

88°  

x  

51°  9.4cm  

6cm  

x  

12m  

67°  

13m  

x   52°  

118°  

45m  

x  

21cm  

48°   61°  

Page 36: fomii unit 4 student packet 10.17.2013...2. Find BC 1. Mark angle with the given value. 2. Label the sides in relation to the given angle (opp, adj, hyp) 3. Circle the known relationships

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4.10  Law  of  Sines  Homework    

Solve for all missing sides and angles in each triangle. Watch out for the ambiguous case. 1.

2.

3. 4. Solve for x

x ≈_______

5. Solve for x

x ≈_______

 6. A large helium balloon is tethered to the ground by two taut lines. One line is 100 feet long and makes an 80° angle with the ground. The second line makes a 40° angle with the ground. How long is the second line, to the nearest foot? How far apart are the tethers?  

x  12  

71°   66°  

28  

x  

72°  

19  

51°  

9.8cm  

71°  

A  B  

C  

42°  

50m  

84°  K  

J  

L  

28m  

62°  

31m  

N  O  

M  

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4.11  Law  of  Cosines  Practice    

Find the missing measure of ΔABC.

1. b = 7; c = 8; ∠ A = 120°; a = ? 2. a = 3; b = 8; c = 7; ∠ C = ?

3. A triangular course for a 30 km yacht race has sides 7km, 9km, and 14 km long. Find the largest angle of the course.

4. A baseball diamond is a 90-ft square. The mound is 60.5 ft from home plate. How far is it from the mound to first base?

5. A vertical pole 20 m tall on a 15° slope is to be braced by two cables extending from the top of the pole to points on the ground 30 m up and 30 m down the slope. How long will the cables be?

   

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4.11  Law  of  Cosines  Homework        1. 2. 3. x ≈_______ x ≈_______ x ≈_______

Y ≈_______ Y ≈_______ Y ≈_______  

 

4.) Two airplanes leave an airport, and the angle between their flight paths is 40º. An hour later, one plane has traveled 300 miles while the other has traveled 200 miles. How far apart are the planes at this time?

5.) Some students in Geometry are assigned the task of measuring the distance between two trees separated by a swamp. The students determine that the angle formed by tree A, a dry point C, and tree B is 27°. They also know that m∠ABC is 85°. If AC is 150 ft, how far apart are the trees?

 

6.) Peter has three sticks measuring 19 inches, 23 inches, and 27 inches. He lays them down to form a triangle. Find the measure of the angle enclosed by the 19 inch and 23 inch sides to the nearest degree.

     

x  

1

8   9  5   x  

39°  8  

y  

12  

y  x  

15  

37°  

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4.12  Solving  Triangles  Practice    

Solve the following problems.

1. Find the area of the triangle whose sides are 12cm., 5cm. and 13cm.

2. A farmer has a triangular field with sides 120 yards, 170 yards, and 220 yards. Find the area of the field in square yards. Then find the number of acres if 1 acre = 4840 square yards.

3.  The course for a boat race starts at point A and proceeds in the direction S 52° W to point B, then in the direction S 40° E to point C, and finally back to A, as shown in the figure. Point C lies 8 kilometers directly south of point A. Approximate the total distance of the race course.

4. During a rescue mission, a Marine fighter pilot receives data on an unidentified aircraft from an AWACS plane and is instructed to intercept the aircraft. The diagram shown below appears on the screen, but before the distance to the point on interception appears on the screen, communications are jammed. Fortunately, the pilot remembers his trigonometry. How far must the pilot fly?              5. A golfer hits a drive 260 yards on a hole that is 400 yards long. The shot is 15° off target. a. What is the distance x from the golfer’s ball to the hole? b. Assume the golfer is able to hit the ball precisely the distance found in part (a). What is the maximum angle θ by which the ball can be off target in order to land no more than 10 yards from the hole?          

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4.12  Solving  Triangles  Homework  Solve the triangles

1. 113 , 25, 21C b c= = =o 2. 60 , 12, 17A b c= = =o

3. Find the area of the triangle with 30 , 12, 9A b c= = =o

4. Raleigh, Durham, and Chapel Hill are three cities in North Carolina that form what is known as the Research Triangle. It is about 18 miles from Raleigh to Durham, 23 miles from Raleigh to Chapel Hill, and 8 miles from Chapel Hill to Durham. Find the area of the Research Triangle.

5. To find the distance AB across a river, a distance BC = 354 m is measured off on one side of the river.It is found that m∠ABC = 112° and m∠BCA = 20°. Find AB. What is the area of triangle ABC? 6. A portion of a barn, in the shape of an isosceles triangle, must be painted. The base of the triangle measures 30 feet long and the legs measure 20 feet each. A can of weatherproofing paint will cover 50 square feet of area. What is the minimum number of cans needed to cover this triangular portion? Justify your answer. 7. Mark is a landscaper who is creating a triangular planting garden. The homeowner wants the garden to have two equal sides and contain and angle of 135°. Also, the longest side of the garden must be exactly 5 m. a. How long is the plastic edging that Mark needs to surround the garden? b. What is the area of the garden?