3. At a zoo, the lion pen has a ring-shaped sidewalk around it. The outer edge of the sidewalk is a circle with a radius of 11 m. The inner edge of the sidewalk is a circle with a radius of 9 m.

(a) Write and simplify an expression or equation for the exact area of the sidewalk.

(b) Find the approximate area of the sidewalk. Use 3.14 to approximate π.

A) A = 40π m²

B) A = 125.6 m²

Explanation:

A) To find the area of the sidewalk, we find the area of the outer ring, find the area of the inner ring, and subtract them.

The area of the outer ring is given by A=πr²; r = 11, so we have A=π (11²) = 121π

The area of the inner ring is given by A=πr²; r=9, so we have A=π (9²) = 81π

The area of the sidewalk would then be A=121π-81π = 40π

B) Using 3.14 for π, we have A=40*3.14 = 125.6 m²