Find the area of the triangle, the rectangle and the semi circle.
Area of the triangle = (bh)/2 = (12*5)/2 = 30
Area of The rectangle = L*W = 40 * 12 = 480
Area of the semi circle = (πr²)/2 = (3.14*6²)/2 = 56.52
Now add them all together = 30 + 480 + 56.52 = 566.52 ft²
Hope this helps :)