The figure below shows the perimeter of a pond: Given that ABC is a semicircle, ACDF is a rectangle, FED is a triangle and the area of
triangle FED is 49 m², calculate
a. the diameter of the semicircle ABC
b. the area of the entire figure.

Explanation:

The diameter of the semi circle = the base of the triangle (shown in pic)

Find he base of the triangle:

Base = (Area x 2)/height
Base = (49 x 2)/7
Base = 7 x 2
Base = 14m

Thus the diameter of the semicircle = 14m.

Calculate area of the entire figure:

Area of whole figure = Area of semicircle + Area of rectangle + Area of triangle

A(whole) = (pi x r^2)/2 + bh + 49
A(whole) = (22/7 x 49)/2 + 18 x 14 + 49
A(whole) = 77 + 252 + 49
A(whole) = 378m^2