The area of a circle is pi times r^2. Because you have a half circle, divide this number by two. They give you the diameter of the circle, 15 m, so divide this in half to get the radius. Therefore to find the area of the semi circle, you’ll multiply 1/2 by pi times 7.5^2. This will give you about 88.36 m^2. To find the area of the trapezoid, you use the formula A=(1/2)(h)(a+b) where h is the height and a and b are the lengths of the bases. Therefore A=(1/2)(12)(12+21). This will give you an area of 198 m^2. Now you can add the two together to get your total area, so 198 + 88.36 = 286.36 m^2.