Find the area of the following composite shape

Explanation

1. This shape represents a rectangle with length = 20 and width = 20.  There are half circles with bending inside this rectangle.  Each half circle has the same diameter = 15.  So, it is a rectangle area where the area of the circle is taken away from it.
2. So the area of the shape could be written as 
   • Area = A_rectangle - A_circle
3. Write rectangle and circle area rules
   • A_rectangle = lw
   • A_{circle =} πr²
4. Calculate rectangle area where l = 20 cm and w = 15 cm
   • A_rectangle = 15 * 20 = 300 cm²
5. Calculate circle area where r = 7.5 cm   (half the diameter which is 15 cm)
   • A_circle = π * 7.5² = 176.715 cm²
6. Calculate the required area
   • Area = 300 - 176.715 = 123.285 cm²