im 8 ch 9.2.7 does it always work -...
TRANSCRIPT
IM 8 Ch 9.2.7 Does It Always Work
CPM Materials modified by Mr. Deyo
Is the triangle a right triangle?
Who is Pythagoras?
Common Core Standard: 8.G.6
IM 8 Ch 9.2.7 Does It Always Work
By the end of the period, I will explain a proof of the Pythagorean Theorem and its converse.
I will demonstrate this by completing Four‑Square notes and by solving problems in a pair/group activity.
Learning TargetTitle: IM8 ‑ Ch. 9.2.7 Does It Always Work? Date:
IM 8 Ch 9.2.7 Does It Always Work
Home Work: Sec. 9.2.7Desc. Date Due
Review & Preview
4 Problems 9‑149, 9‑150, 9‑151, 9‑154
IM 8 Ch 9.2.7 Does It Always Work
IM 8 Ch 9.2.7 Does It Always Work
Vocabulary1) right triangle
2) leg(s)(a & b)
3) hypotenuse (c)
4) Pythagorean Theorema2 + b2 = c2
IM 8 Ch 9.2.7 Does It Always Work
IM 8 Ch 9.2.7 Does It Always Work
9.2.7 Does It Always Work? You have seen that you can find the missing side of a right triangle using the Pythagorean Theorem. To show that it is always true, no matter how long the sides are, it must be proven. There are over 100 different ways to prove this important relationship. Today you will look at two ways to prove the Pythagorean Theorem. As you may remember, the Pythagorean Theorem states that in a right triangle with sides a and b, and hypotenuse c, a2 + b2 = c2.9145 Obtain the Lesson 9.2.7A Resource Page from your teacher. For additional support, watch Pythagorean Proof Video
b
ac
b
a c
http://www.cpm.org/pdfs/stuRes/CC3/chapter_09/CC3%20Lesson%209.2.7A%20RP.pdf
http://www.cpm.org/media/Pythagorean_Theorem.m4v
IM 8 Ch 9.2.7 Does It Always Work
9145a,b) Start by cutting out four copies of the right triangle with legs labeled a, b, and hypotenuse labeled c units.a) First, arrange the triangles to look like the diagram at right. Draw this diagram on your paper. Explain why the area of the unshaded region is c2.b) Will moving the triangles within the bold outer square change the total unshaded square?
b
ac
b
a c
http://www.cpm.org/pdfs/stuRes/CC3/chapter_09/CC3%20Lesson%209.2.7A%20RP.pdf
http://www.cpm.org/media/Pythagorean_Theorem.m4v
IM 8 Ch 9.2.7 Does It Always Work
9145) c) Move the shaded triangles to match the diagram at right. In this arrangement, tell why the total area that is unshaded is a2 + b2.d) Write an equation that relates the unshaded region in part (a) to the unshaded region in part (b).
b
ac
b
a c
http://www.cpm.org/pdfs/stuRes/CC3/chapter_09/CC3%20Lesson%209.2.7A%20RP.pdf
http://www.cpm.org/media/Pythagorean_Theorem.m4v
IM 8 Ch 9.2.7 Does It Always Work
9146. Here is another proof of the Pythagorean Theorem for you to try. Obtain the Lesson 9.2.7B Resource Page from your teacher. a) Start with two squares as shown here. What is the total area?
c) Cut out the shaded triangles shown in the diagram at right. Then work with your team to determine how to arrange the shaded triangles and the unshaded portion of the original figure to create a square. What is the area of the square? How do you know?
a
b
ca
bc
b) Use a ruler or another piece of paper to place a mark of length b on the bottom left side of the larger square. Then draw the dotted lines as shown in the diagram at right to create two right triangles. How do you know that the legs of both triangles are legs a and b? Label each hypotenuse c.
d) How does what you have done in this problem prove the Pythagorean Theorem?
IM 8 Ch 9.2.7 Does It Always Workhttp://www.cpm.org/pdfs/stuRes/CC3/chapter_09/CC3%20Lesson%209.2.1A%20RP.pdf
9.2.1A#951
147b)
IM 8 Ch 9.2.7 Does It Always Work
9147. The converse of a theorem reverses the evidence and the conclusion. The Pythagorean Theorem states that in a right triangle with legs of a and b, and hypotenuse c, that a2 + b2 = c2.a) State the converse of the Pythagorean Theorem.
b) Look back at your work from problem 951. What can you conclude about a triangle if a2 + b2 = c2?
c) Why is this not a proof of the converse of the Pythagorean Theorem?
IM 8 Ch 9.2.7 Does It Always Work
9148. Graph the points A(−2, 2) and B(1, −2). Then find the distance between them by creating a right triangle (like a slope triangle) and computing the length of the hypotenuse.
IM 8 Ch 9.2.7 Does It Always Work
9149. Use a graph to find the distance between the points C(−4, −1) and D(4,1). http://homework.cpm.org/cpmhomework/homework/category/CC/textbook/CC3/
chapter/Ch9/lesson/9.2.7/problem/9149https://www.desmos.com/calculator/4h2mt3s7qy
IM 8 Ch 9.2.7 Does It Always Work
9150. Jack has a tree in his backyard that he wants to cut down to ground level. He needs to know how tall the tree is, because when he cuts it, it will fall toward his fence. Jack measured the tree’s shadow, and it measured 20 feet long. At the same time, Jack’s shadow was 12 feet long. Jack is 5 feet tall.
a) How tall is the tree?
http://homework.cpm.org/cpmhomework/homework/category/CC/textbook/CC3/chapter/Ch9/lesson/9.2.7/problem/9150
Tree Jack
b) Will the tree hit the fence if the fence is 9 feet away?
IM 8 Ch 9.2.7 Does It Always Work
9151. Examine the diagrams below. What is the geometric relationship between the labeled angles? What is the relationship of their measures? After you determine the relationship of their measures, use the relationship to write an equation and solve for x.
a) b)
http://homework.cpm.org/cpmhomework/homework/category/CC/textbook/CC3/chapter/Ch9/lesson/9.2.7/problem/9151
IM 8 Ch 9.2.7 Does It Always Work
9152. On graph paper, graph the system of equations below. Graph
y = x + 1
What's the solution of the system? ( , )If there is no solution, explain why not.
https://www.desmos.com/calculator/8ltjjowa9q http://homework.cpm.org/cpmhomework/homework/category/CC/textbook/CC3/chapter/Ch9/lesson/9.2.7/problem/9152
25
y = x 225
IM 8 Ch 9.2.7 Does It Always Work
9153. A principal made the histogram at right to analyze how many years teachers had been teaching at her school.
c) What is the probability that a teacher on the staff has been there for fewer than 5 years?
b) If the principal randomly chose one teacher to represent the school at a conference, what is the probability that the teacher would have been teaching at the school for more than 10 years? Write the probability in two different ways.
a) How many teachers work at her school?
http://homework.cpm.org/cpmhomework/homework/category/CC/textbook/CC3/chapter/Ch9/lesson/9.2.7/problem/9153
IM 8 Ch 9.2.7 Does It Always Work
9154a,b. Simplify each expression.
a) b)
http://homework.cpm.org/cpmhomework/homework/category/CC/textbook/CC3/chapter/Ch9/lesson/9.2.7/problem/9154
12 5
7 10
94
13( )
IM 8 Ch 9.2.7 Does It Always Work
9154c,d. Simplify each expression.
c) d*)
http://homework.cpm.org/cpmhomework/homework/category/CC/textbook/CC3/chapter/Ch9/lesson/9.2.7/problem/9154
35
16
95
10 3
( )( )