use the Cofunction Theorem to fill in the blank so that the

use the Cofunction Theorem to fill in the blank so that the expression becomes a true statement

cos y = sin

A) 180° + y

B) 90° - y

C) 180° - y

D) 45° + y

Solution

Recall that sin(90° - x)= cos(x)

so using this fact:

cos y= sin (90° - y)

Hence option (B) is correct.