# Math Help - cosine thing

1. ## cosine thing

Given that $x$ takes a value near $\frac{\pi}{2}$, explain why $cosx = \frac{\pi}{2}-x$

2. Hello,

cos(x)=sin(pi/2-x)

pi/2-x is near 0, because x is near pi/2

We know that sin(y) ~ y when y is near 0.

Hence cos(x) ~ pi/2-x