to find the entire area of the figure, you'll have to split it up into two parts:
a. triangle
b. semi-circle
therefore, the formula for the area of a triangle is 1/2(base)(height). in simpler terms, it means to multiply 1/2 by the base and the height. in this case, multiply 1/2 x 5 x 12, which gives you 60/2, which ultimately gives you 30.
to find the area of the semi circle, use the area formula for a circle and divide the area by 2. the formula is: π. so, plug in your lengths. this gives you, π(5)^2. divide this by two. you should get an answer of 9.82
finally, add your two areas (30+9.82), which equals 39.82