pg. 323/361 homework pg. 362 #39 – 47 odd, 51, 52 memorize trig. info #2qiv#4qiii#6qiii...
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Pg. 323/361 Homework• Pg. 362 #39 – 47 odd, 51, 52
Memorize Trig. Info
• #2 QIV #4 QIII #6 QIII• #8 -250° #10 470°• #12 338°, 698°, -382°, -742° #14 210°, 570°, -510°, -870°• #16 11π/4, -5π/2 #18 29π/6, -19π/6• #20 π/4, 9π/4, -15π/4, -23π/4 #22 67°, 157°• #24 78°, 168° #26 5π/12, 11π/12 #28 π/14, 4π/7• #30 90°, π/2 #32 135°, 3π/4 #34 0°, 0, 2π• #36 -120°, -2π/3 #38 -600°, -10π/3 #40 -1260°, -7π• #42 π/3 #44 7π/6 #46 11π/6• #48 59π/90 #50 249π/180 #52 810/π• #1 #2 #3 8/7• #4 7/8 #5 #6• #7• #8 11/15 #9 #10• #11 #12 #13 15/11
8113
7113
1137
1138
2 2615
152 26
2 2611
112 26
113 1137 8 7 8, , , , ,8 7 8 7113 113
6.5 Trig Functions of an Acute Angle
Trig Functions• The six trig functions of any
angle 0° < Ɵ < 90° are defined as follows:
• Also, we know that from the basic three trig functions:
sin cot
cos sec
tan csc
opp adj
hyp opp
adj hyp
hyp adj
opp hyp
adj opp
1cot
tan1
seccos1
cscsin
6.5 Trig Functions of an Acute Angle
Triangle Trig• We use right triangles
because they allow us to use the Pythagorean Theorem, which makes solving a much easier process!
• Because 30°, 45° and 60° occur frequently, we will learn and memorize those triangles!!
• If c = 2, determine the lengths of a and b and find the six trig values at 30° and 60°.
6.5 Trig Functions of an Acute Angle
More Trig Triangles• If a = 1, determine the
length of c and find the six trig values.
Cofunctions of Complementary Angles
• If Ɵ is any acute trig angle, a trig function value of Ɵ is equal to the cofunction of the complement of Ɵ, as follows:
sin cos cot tan2 2
cos sin sec csc2 2
tan cot csc sec2 2
6.5 Trig Functions of an Acute Angle
Example:• Show that
are cofunctions. • Let Ɵ be an acute angle
such that sin Ɵ = 5/6. Find all the trig functions of Ɵ.
• One angle of a right triangle measures 38°, and the hypotenuse has length of 17. Find the measures of the remaining sides.
sin cos2
6.5 Trig Functions of an Acute Angle
Example:• They hypotenuse and one
leg of a triangle measure 12 and 7 respectively. Find the measure of angle Ɵ formed by these two sides.
Trig Functions of Any Angle• Let Ɵ be an angle in
standard position, P(x, y) a point other than the origin on the terminal side of P, and r = The six trig values of Ɵ are defined as follows:sin cos tan
sec csc cot
y x y
r r xr r x
x y y
2 2x y
6.5 Trig Functions of an Acute Angle
Example:• Find the values of the six
trig functions at an angle Ɵ in standard form with point P(4, 7) on its terminal side.
• **Note** If an angle does not appear acute in the first quadrant, you can work in any of the four quadrants to make the angle acute!!
• Find the values of all six trig functions and the angle of measure of angle Ɵ, where P(-3, 2) is a point on the terminal side of Ɵ.
• Find all the values of all six trig functions for the quadrantal angles of:
30, , , , 22 2