Answer:
31.16
Step-by-step explanation:
Perimeter of the shaded portion = Perimeter of the rectangle - Perimeter of the 2 circles
Length of rectangle = 13
Width = 2d
d is the diameter of the circle = 2(6) = 12
Perimeter of the rectangle = 2(L+W)
Perimeter of the rectangle = 2(13+12)
Perimeter of the rectangle = 2(25)
Perimeter of the rectangle = 50
Perimeter of the semi-circle = πd/2
Perimeter of the circle = 3.14(6)/2
Perimeter of the circle = 18.84/2
Perimeter of the 2 circles = 2(18.84)/2
Perimeter of the 2 circles = 18.84
Perimeter of the shaded portion = 50 - 18.84
Perimeter of the shaded portion = 31.16