find the maximum and minimum values of $r=\sin(3\theta)\cos(2\theta)$
I’m studying calculus, the chapter in my book is about graphing in polar coordinates.
In order to find the maximum and minimum values of $r$ I need to get a value of $\theta$ for which $$r’=-2\sin(3\theta)\sin(2\theta) + 3\cos(3\theta)\cos(2\theta)=0$$ According to my book the answer is max $=1$ And min $=-1$ I’m not sure how to get this, could anyone help me?
Note. I already tried with some trigonometric identities for reducing the equation but cannot get anywhere.