Question

The area of a trapezoid is 864cm². It has a height of 24 cm, and the length of one of its bases is 30 cm. What is the length of the other base?​

Answer 1

The area A of a trapezoid with height h and bases b₁ and b₂ is equal to the average of the bases times the height:

A = (b₁ + b₂) h / 2

We're given A = 864, h = 24, and one of the bases has length 30, so

864 = (b₁ + 30) 24 / 2

864 = (b₁ + 30) 12

864 = (b₁ + 30) 12

72 = b₁ + 30

b₁ = 42