Question

Suppose sin(θ)=1/4, where θ is in radians. Find exact values (as fractions, not decimal approximations) for the following.

(a) cos(π2−θ) =

Answer 1

Just by using associate angles identities, you have

$\cos\left(\dfrac{\pi}{2} - \theta\right) = \sin(\theta)$

So, you also have

$\cos\left(\dfrac{\pi}{2} - \theta\right) = \sin(\theta) = \dfrac{1}{4}$