3. 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)

(b)

Step-by-step explanation:

(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 .

(a) The sidewalk area is the difference in the area of outer circle and inner circle.

Use formula for the area of the circle:

The difference is

(b) Use approximation then