Question

30.54

Answer 1

Answer: Choice 2)  sin(B) = cos(90-B)

Explanation:

The rule is that

sin(A) = cos(B)

if and only if A+B = 90.

Solving for A gets A = 90-B

So we end up with

sin(90-B) = cos(B)

which is the same as

cos(B) = sin(90-B)