Question

If sin∠X = cos∠Y and m∠X = 72°, what is the measure of ∠Y?

a. 18°
b. 72°
c. 90°
d. 108°

Answer 1

The answer is 18.

Explanation:

90-72=18

Answer 2

A. 18°

Explanation:

Using the cofunction identity

sin x = cos(90 - x)

Hence

sin72° = cos(90 - 72)° = cos18° ⇒ ∠Y = 18°