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The figure below shows a round plate that is white with a 2-inch gray border around it

What is the area of just the gray border?

The figure below shows a round plate that is white with a 2-inch gray border around-example-1
User Kalhartt
by
7.5k points

1 Answer

2 votes

Given:

Radius of small circle = 4 in.

Width of gray border = 2 in.

To find:

The area of the gray border.

Solution:

We have, radius of small circle:


r=4\text{ in.}

The width of gray border is 2 in. So,t he radius of the larger circle is:


R=4+2\text{ in.}


R=6\text{ in.}

Now, area of gray border is the difference for area of larger circle and smaller circle.


A=\pi R^2-\pi r^2


A=\pi (R^2-r^2)

Substituting
r=4,\ R=6 in the above formula, we get


A=\pi (6^2-4^2)


A=\pi (36-16)


A=\pi (20)


A=20\pi

The area of the gray border is
20\pi square inches. Therefore, the correct option is D.

User Mark Skelton
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