If θ and φ are each first quadrant angles,which of the following must be true if sin θ = cos φ?
A)θ + φ = π rad
B)θ + φ = 90°
C)θ - φ = π/2 rad
D)θ = φ

Question

Quizplus · Accepted Answer

In the first quadrant, both sin and cos are positive. Since sin θ = cos φ, we can write θ = 90° - φ. Thus, θ + φ = 90°, and this is the only choice that must be true.

If θ and φ Are Each First Quadrant Angles,which of the Following