I think the shaded region for this problem will the part of the circle that is not covered by the triangle. First, determine the area of the circle by the equation,
A = πD²/4
Substituting the given diameter,
A = π(16 ft)²/4 = 200.96 ft²
Then, determine the area of the triangle with the equation,
A = bh/2
Since the base of the triangle is the diameter, b = 16 ft. Then, its height will be half the height and that will be equal to 8 ft. Substituting,
A = (16 ft)(8 ft) / 2 = 64 ft²
The difference between the two areas is 136.96 ft².