Perimeter is the length of the border. The best way to find it here is to split the figure up into a semicircle and a trapezoid.
The radius of the semicircle is 9 in. so its perimeter is 2pir/2 = 9pi in.
The perimeter of the trapezoid can be found by adding the lengths of all sides. The bottom side is 2 times the radius of the semicircle, 18 inches. Add this to the other lengths: 5 in, 12 in, 5 in.
The total perimeter is then 40 + 9pi.
