Set 3: Trigonometry (Advanced)

[Variation 1] **Choice B is the best answer.** cos squared = 1 - sin squared = 1 - 9/25 = 16/25. cos = 4/5

Explanation

Answer: B

PROBLEM

Recent studies show that if sin(theta) = 3/5 and theta is in the first quadrant, find cos(theta).

If sin(theta) = 3/5 and theta is in the first quadrant, find cos(theta).

3/4

4/5

✓ Correct

5/4

3/5

Detailed Explanation

[Variation 1] Choice B is the best answer. cos squared = 1 - sin squared = 1 - 9/25 = 16/25. cos = 4/5

Why others are wrong:

A: 3/4 is incorrect because it does not satisfy the equation.

C: 5/4 is incorrect because it does not satisfy the equation.

D: 3/5 is incorrect because it does not satisfy the equation.