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Trigonometry Week 12 Test Grade Report

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Subject
Trigonometry
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Exam Practice
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Trigonometry Week 12 Test - Grade Report
Score:
92% (92 of 100 pts)
Submitted:
Jul 24 at 10:03am
Question: 1
Grade: 1.0 / 4.0
Given that tanθ=−tanθ=−7676 and π2<θ<ππ2<θ<π, find the exact values of the
trigonometric functions.
csc2θ=csc2θ= -85/84 (17%)
sec2θ=sec2θ= -85/13 (17%)
cot2θ=cot2θ= 13/84 (17%)
Solution
Draw the angle in quadrant 2 since π2<θ<ππ2<θ<π.
Use the Pythagorean Theorem to find the unknown side of the triangle.
In this case, the hypotenuse has length 85−−√85.
Substitute the lengths of the three sides of the right triangle into the double-angle formulas
to find each exact value.
sin2θsin2θ
=2sinθcosθ=2sinθcosθ
=2⋅785−−√⋅−685−−√=2⋅785⋅−685
=−8485=−8485
cos2θcos2θ
=cos2θ−sin2θ=cos2θ−sin2θ
=(−685−−√)2−(785−−√)2=−6852−7852
=3685−4985=3685−4985
=−1385=−1385

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tan2θtan2θ
=2tanθ1−tan2θ=2tanθ1−tan2θ
=2(−76)1−(76)2=2−761−−762
=−1461−4936=−1461−4936
=−146−1336=−146−1336
=8413=8413
Use the reciprocals of sin2θsin2θ, cos2θcos2θ and tan2θtan2θ to find the vlues
of csc2θcsc2θ, sec2θsec2θ, and cot2θcot2θ.
Therefore, csc2θ=−8584csc2θ=−8584, sec2θ=−8513sec2θ=−8513,
and cot2θ=1384cot2θ=1384.
Question: 2
Grade: 1.0 / 4.0
What is the value of cos(−22.5°)cos−22.5°?
2+2–√−−−−−−√22+22 (100%)
Solution
cos(−22.5°)=cos(−45°2)cos−22.5°=cos−45°2
Write −22.5 as a
fraction with a
denominator 2.
=1+cos(−45°)2−−−−−−−−−−−=1+cos−45°2
Half-Angle
Formula
=1+2–√22−−−−−−− =1+222
Evaluate
cos(−45°).
=2+2–√22−−−−−−− =2+222
Common
denominator.
=2+2–√4−−−−−−√=2+24
Simplify.
=2+2–√−−−−−−√2=2+22
Simplify the
denominator.
Therefore, cos−22.5∘=2+2–√−−−−−√2.cos−22.5∘=2+22.
Question: 3
Grade: 1.0 / 4.0
Use the product-to-sum formula to write cos6xsin9xcos6xsin9x as a sum or difference.
12sin15x+12sin 3x12sin15x+12sin 3x (100%)

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Trigonometry Week 12 Test - Grade Report Score: 92% (92 of 100 pts) Submitted: Jul 24 at 10:03am Question: 1 Grade: 1.0 / 4.0 Given that tanθ=−tanθ=−7676 and π2 ...
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