Find the missing side of the right triangle using Pythagorean Theorem:
10^2 =8.7^2 +x^2;
x^2=100-75.69=24.31
x= sqrt 24.31~ 4.93
Area of trapezoid is area of triangle+area of a rectangle.
A=(8.7x4.93/2)+(12x4.93)
A=80.6055 ~81 ft^2
Ok so you do height times width
