# How do you find the critical points to graph  f(x) = 4 sin(x - pi/2 ) + 1?

Feb 28, 2016

0 and 2$\pi$ in the interval $\left(0 , 2 \pi\right]$
$f ' \left(x\right) = 4 \cos \left(x - \frac{\pi}{2}\right)$
At critical points f'(x)=0, that gives $\cos \left(x - \frac{\pi}{2}\right) = 0$
$x - \frac{\pi}{2} = \frac{\pi}{2} , \frac{3 \pi}{2}$
$x = \pi , 2 \pi$ in the interval $\left(0 , 2 \pi\right]$