If the base of a semicircle is a feet What is its perimeter?

The circumference of a circle = 2π r = π a (where a is the base of the semicircle and is also the diameter of the circle)

The perimeter of the semicircle = half the perimeter of the circle + the base length

The perimeter of the semicircle = πa/2 + a = a(1 + π /2) feet