### Home > MC2 > Chapter 6 > Lesson 6.1.1 > Problem6-11

6-11.

The diameter of the large circle is $18$ cm.

1. What is the area of the shaded circle?

2. What steps did you do need to do to find the answer?

Identify what part of the diagram $18$ cm represents.

What would the radius of the large circle be?

Notice that the radius of the larger circle is $5$ cm more than the radius of the shaded circle.

Subtract the radius of the large circle by $5$ cm to find the radius of the shaded circle: $9$ cm $− 5$ cm $= 4$ cm. Now that you have the radius of the shaded circle, recall how to use that to find the area.

$A = r^2π$

$A = (4)^2π$
The area is approximately $50.27$ cm$^{2}$

Explain what you did in part (a).