Answer
$ cos(\frac{\pi}{2}-x)=sinx$
Work Step by Step
Need to prove $ cos(\frac{\pi}{2}-x)=sinx$
$ cos(A-B)=cos A cos B+sinA sin B$
Thus,
$ cos(\frac{\pi}{2}-x)=cos \frac{\pi}{2} cos x+sin\frac{\pi}{2} sin x$
$ cos(\frac{\pi}{2}-x)=0*cos x+1*sin x$
Hence, $ cos(\frac{\pi}{2}-x)=sinx$
