Question: how to find the perimeter of a window?
Answer: Then we know that the perimeter of the window is equal to x + 2h + outer perimeter of semi-circle. Since the semi-circle in our Norman window has radius x/2, its contribution to the perimeter of the window is half the circumference of a circle of radius x/2: 1 2 ( 2π x 2 ) = π x 2 .