2
Answer: BSet 2: Trigonometry (Advanced)
Explanation
PROBLEM
Recent studies show that if sin(theta) = 8/17 and theta is in the first quadrant, find cos(theta).
If sin(theta) = 8/17 and theta is in the first quadrant, find cos(theta).
A.
17/15
B.✓ Correct
15/17
C.
8/17
D.
8/15
Detailed Explanation
[Variation 1] Choice B is the best answer. cos squared = 1 - sin squared = 1 - 64/289 = 225/289. cos = 15/17
Why others are wrong:
A: 17/15 is incorrect because it does not satisfy the equation.
C: 8/17 is incorrect because it does not satisfy the equation.
D: 8/15 is incorrect because it does not satisfy the equation.