Question

Grace makes a cheese pizza with wide crust. the diameter of the pizza is 16 inches. the width of the crust is 2.2 inches. what is the area of the portion with cheese

Answer 1

The area of a disc is given by the formula $\pi r^2$ wherein r is the radius. 
First compute the radius: $\frac{16}{2}=8$
Then compute the area like this:
$\pi r^2=\pi 8^2=201\text{ }inches^2$

The area of the portion with cheese is 201 inches^2

Answer 2

The area of the portion with cheese is calculated by determining the radius of the circle of the portion with cheese and applying the formula for the area of a circle. Since the diameter of the pizza is 16 inches, the radius is 8 inches, however the radius of the circular portion with cheese is smaller since 2.2 inches of the radius is actually the width of the crust. The radius of the circular portion with cheese is 8-2.2=5.8 inches. The area of the cheese portion is thus: pi(5.8^2 ) = 105.68 sq. inches (rounded to two decimal places).