Answer
(a) See graph, it is a circle.
(b) $(x-4)^2+y^2=16$
Work Step by Step
(a) See graph, it is a circle centered at $(4,0)$ with a radius of $4$.
(b) Use the conversion formula $cos\theta=\frac{x}{r}, r^2=x^2+y^2$ we have $r=8cos\theta=8\times\frac{x}{r}$ or $r^2=8x$ which gives $x^2-8x+y^2=0$ or $(x-4)^2+y^2=16$
