### Home > PC > Chapter 5 > Lesson 5.2.1 > Problem 5-53

5-53.

The surface area of a sphere is directly proportional to the square of the radius

*.*

Express

as a function of.Do not forget the constant of proportionality (

).Solve for the particular value of

if the surface area iswhen the radius is cm. Then find the surface area when the radius is cm. Substitute the given point

into your function in part (a) to find .

Then use the resulting equation to find the surface area whencm.