Solving for zero using differentiation I need help finding the min and max to the equation $y'= 4.9385 \cos(0.017(x-80)).$ I've tried this by making $y' = 0$ and tried to solve for $x$ but I don't understand how to do it.
So, can someone please help find the min and max for $0 = 4.9385 \cos(0.017(x-80))$ ?

Given the equation:
$$ y = A \sin( \kappa\, (x-a) ) $$
The min max of $y$ is $$ y' = A \kappa \cos(\kappa\, (x-a) ) =0$$
This is solved by $\cos(\kappa\, (x-a) )=0$ or
$$ \kappa\, (x-a)  = \frac{\pi}{2} + n \pi $$
