15. Let the radius of the semi-cirlce be x and the length of rectangle be y.
Perimeter = pi*2x/2 (semi-circle, circumference = pi*diameter = pi*2x) + 2y (lengths of rectangle) + 2x (other side of rectangle which happens to be the diameter of the circle)
So P = pi*x + 2y + 2x = 4m (given to...