How do you find the area of the shaded region in the diagram below?

enter image source here

1 Answer
Nov 28, 2017

Area of the shaded portion = r^2

Explanation:

Circumference of the whole circle = 2pir
Circumference of the curved portion of the shaded area = 2r
Ratio of circumferences = (2r)/(2pir )= 1/pi

Areas of shaded region and the whole circle will be in the proportion (1/pi)

Area of the whole circle = pi r^2

:. Area of the shaded portion
= (cancel(pi )r^2) /cancel (pi) = r^2