A parabolic tunnel has the shape of a parabola in cross-section, with one axis being symmetric (the width) and the other axis being the height at the center. To find the cross-sectional area of the parabolic tunnel, we can use the formula for the area of a parabola:
Area = (1/2) x Width x Height
Given that the width of the parabolic tunnel is 20 feet and the height at the center is 12 feet, we can substitute these values into the formula:
Area = (1/2) x 20 x 12 = 120 square feet.
So the cross-sectional area of the parabolic tunnel is 120 square feet.