Chapter 1.7, Problem 90PPE

To determine

To Translate: The sentence “Four times $\pi$ times the radius squared is the surface area of a sphere ” into a formula.

Answer to Problem 90PPE

The surface area of a sphere is $4\cdot \pi \cdot r^2$ .

Explanation of Solution

Given information:

The sentence “Four times $\pi$ times the radius squared is the surface area of a sphere”.

Calculation:

Let the radius of the sphere be “r”

  $r$

squared can be represented by:

  $r^2$

Times can be represented by “ $\cdot$ ”

So, Four times $\pi$ times the radius squared can be written as

  $4\cdot \pi \cdot r^2$

Therefore the surface area of a sphere is

  $4\cdot \pi \cdot r^2$