Mathematics

Problem

For the polar curve

r=4\cos\theta+3\sin\theta

: (a) find all critical angle(s)

\theta

where

\displaystyle \frac{dr}{d\theta}=0

, (b) use

\displaystyle \frac{d^{2}r}{d\theta^{2}}

to classify each critical point, and state the corresponding extreme value of

r