8. a brick oven has an opening as shown. what is the area of the entire opening?

a. 22.1 ft2
b. 20 ft2
c. 16.8 ft2
d. 13.5 ft2

As shown in the picture above, you are given an opening of the brick with a combination of a rectangle and a semicircle. To find the area of the total opening, you need to have the formula of the area of the rectangle and the semicircle.

A (rectangle) = LW
A (rectangle) = (4ft) (2.5ft)
A (rectangle) = 10 ft²

A (parabola) = 2/3ab
A (parabola) = 2/3 (1.25) (4ft)
A (parabola) = 5 (2/3) 
A (parabola) = 3.33ft²

A (total area) = rectangle + parabola
A (total area) = 10 + 3.33
A (total area) = 13.33ft²

The answer is letter D.