Question

Find area of the cross section of the dam pictured below

Answer 1

• (w + h cotθ)h

Explanation:

Cross section is the isosceles trapezoid.

Area of trapezoid:

• A = 1/2(a + b)h

We have one of the bases and the height.

Let the difference of the base lengths is x.

We have:

• (x/2)/h = cot θ ⇒ x = 2h cot θ

The area is:

• A = 1/2(w + w + 2h cot θ)h = (w + h cotθ)h