Question

Given the two concentric circles with center N below, LN = 13.5. Find the area of

the shaded region. Round your answer to the nearest tenth if necessary.

Answer 1

371.5 square units.

Explanation:

the shaded region is a ring-shaped region between the two concentric circles, we can find the area of the shaded region as follows:

The area of the large circle is given by:

Area of large circle = π × r^2

where r is the radius of the large circle, which is 13.5.

Area of large circle = 22/7× (13.5)^2

Area of large circle ≈ 572.78

The area of the small circle is given by:

Area of small circle = π × r^2

where r is the radius of the small circle, which is 8.

Area of small circle = 22/7× (8)^2

Area of small circle ≈ 201.14

The area of the shaded region is the difference between the area of the large circle and the area of the small circle:

Area of shaded region = Area of large circle - Area of small circle

Area of shaded region ≈ 572.78 - 201.14

Area of shaded region ≈ 371.5

Therefore, the approximate area of the shaded region is 371.5square units.

Answer 2

The area of the shaded region is 371.5 square units to the nearest tenth.

Explanation:

To find the area of the shaded region of two concentric circles with a common center, subtract the area of the smaller circle from the area of the larger circle.

The formula for the area of a circle is A = πr², where r is the radius of the circle.

From inspection of the given diagram:

• The radius of the larger circle is LN = 13.5.
• The radius of the smaller circle is MN = 8.

Therefore, the area of the shaded region is:

`\begin{aligned}\textsf{Area of shaded region}&=\textsf{Area of larger circle}-\textsf{Area of smaller circle}\\&=\pi (13.5)^2-\pi (8)^2\\&=182.25 \pi - 64 \pi\\&=118.25 \pi\\&=371.493331...\\&=371.5\; \sf unit^2\;\;(nearest\;tenth)\end{aligned}`

The area of the shaded region is 371.5 square units to the nearest tenth.