Question

Find the area of the shaded region. Round to the nearest tenth if necessary.

Answer 1

Find the area of the large circle, and subtract the areas of the three smaller circles.

Large circle: diameter = 22 cm; radius = 11 cm

A = pi r^2 = pi * (11 cm)^2 = 121pi cm^2

Circle with 7 cm radius:

A = pi r^2 = pi * (7 cm)^2 = 49pi cm^2

Two small circles:
The largest circle has diameter = 22 cm.
The next larger circle has radius = 7 cm, so diameter = 14 cm
22 cm - 14 cm = 8 cm
The two smallest circles have a sum of diameters = 8 cm
Each smallest diameter = 4 cm, so each smallest radius = 2 cm
A = pi r^2 = pi * (2 cm)^2 = 4pi cm^2 (for each of the smallest circles)

Shaded area = 121pi cm^2 - 49pi cm^2 - 4pi cm^2 - 4 pi cm^2

Shaded area = 64pi cm^2 = 64 * 3.14159... cm^2 = 201.0619... cm^2

Answer: The shaded area is 201.1 cm^2