This is a figure composed of a semicircle and a right triangle.
Triangle:
The area of a triangle is denoted by A = (1/2) * B * h, where b is the base and h is the height. Here, the base is actually also the radius of the semicircle, which is 4. The height is 9. Plug these in: A = (1/2) * 4 * 9 = 36/2 = 18 yd squared.
Semicircle:
The area of a semicircle is denoted by A = , where r is the radius. Here the radius is 4. So: A = ≈ 25.13 yd squared.