At the mission museum Mrs. Perez visited over break, there is a pond like the one below that has a ring shaped sidewalk around it. The outer edge of the sidewalk is a circle with a radius of 10 m. The inner edge of
the sidewalk is a circle with a radius of 8 m.
(a) Write and simplify an expression for the exact area of the sidewalk.

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