Question

If you built a a sidewalk around a lion's den and it had a radius of 11 m on the outer edge of the sidewalk and a radius of 9 m and the inner edge of the sidewalk . write and simplify the expression for the exact area of the sidewalk, and find the approximate area of the sidewalk using 3.14 to approximate pi.

Answer 1

Area of the first semicircle:

`(\pi11^2)/(2)`
Area of the second semi circle:

`(\pi9^2)/(2)`
Substract the two values:

`(\pi11^2)/(2) - (\pi9^2)/(2)`
Approximative value:
63m^2