Question

A cake has CIRCUMFERENCE of 20.41 inches. What is the AREA of the cake? Use 3.14 to approximate n. Round to the nearest tenth, but enter it without a label. Enter your answer in the box.

Answer 1

Circumference of a circle is

$P=2\times\pi\times r$

where r is the radius, and P the value of circunference or perimeter, then replace P and pi to solve r

$\begin{gathered} 20.41=2\times3.14\times r \\ 20.41=6.28r \\ \frac{20.41}{6.28}=\frac{6.28}{6.28}r \\ \\ 3.25=r \end{gathered}$

radius is 3.25 inches

Area

Apply formula of the area of a circle

$A=\pi\times r^2$

repalce pi and r to find the area

$\begin{gathered} A=3.14\times(3.25)^2 \\ A=3.14\times10.5625 \\ A=33.16625 \end{gathered}$

The rounded value of the area is 33.2 square inches