CPM Homework Help : MC2 Problem 6-11

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

What is the area of the shaded circle?
What steps did you do need to do to find the answer?

Hint (a):

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

More Help 1 (a):

What would the radius of the large circle be?

More Help 2 (a):

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

More Help 3 (a):

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.

More Help 4 (a):

$A = r^2π$

Answer (a):

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

Hint (b):

Explain what you did in part (a).