Question

If b is the measure of an acute angle and cos b = 0.75, then:

(1) sin(b - 90°) = 0.75

(2) sin(90° - b) = 0.75

(3) sin b = 0.75

(4) sin b = 0.25

Answer 1

option (2)

Explanation:

Using the cofunction identity

cosx = sin(90 - x) , then

cosb = sin(90 - b) = 0.75