Question

The image below shows a 8x7 rectangle from which a circle with a radius of 3 units has been cut. What is the approximate area of the blue region to nearest tenth.

Answer 1

Are of the blue region is equal to the area of the circle subtracted from the area of the rectangle:

$A_B=A_R-A_C$

Area of a rectangle:

$A_R=L\cdot W$

L is the lenght

W is the width

Area of a circle:

$A_C=\pi\cdot r^2$

r is the radius

The area of the blue region is:

$\begin{gathered} A_B=(L\cdot W)-(\pi\cdot r^2) \\ \\ A_B=8\cdot7-\pi\cdot3^2 \\ A_B=56-9\pi \\ A_B\approx27.7 \end{gathered}$Then, the area of the blue region is approximately 27.7 square units