Question

Tori is studying Japan and decides to paint a Japanese flag. She first paints a white rectangle that is 36 inches long and 24 inches wide. Then in the center , she paints a red circle with a circumference of 43.96 inches. Use 3.14 for pi.


A) In the finished painting , how many square inches is the white area? Round your answer to the nearest tenth.

b) In the finished painting , how many square feet is the white area? Display two different ways to get your answer. Round your answer to the nearest hundredth.

Answer 1

First compute the area of the rectangle:
$24\times36=864inches^2$
We have to find the radius of the circle:
circonférence of circle given radius is:  $C=2\pi r$
We get the equation:$2\pi r=43.96$
Solving the above equation for r we get: $r=7$
Compute the area of the circle like this: $\pi r^3=\pi7^2=154inches^2$
The white area is the difference of the area of the rectangle and the area of the circle:
$864-154=710inches^2$