5.7 Exercise 89

Determine the function described and then use it to answer the question.

The surface area, $A ,$ of a cylinder in terms of its radius, $r ,$ and height, $h ,$ is given by $A = 2 \pi r^{2} + 2 \pi r h .$ If the height of the cylinder is 4 feet, express the radius as a function of $A$ and find the radius if the surface area is 200 square feet.