Math
posted by Beatrice .
The area of a trapezoid is 66 sq units. The length of its longer base is 4 units longer than the length of its shorter base, and its height is 7 units longer than the length of its shorter base. Find the length of each base and the height of the trapezoid.

you know that with bases b and c, and height h, a trapezoid has area
a = h * (b+c)/2
Just plug in your numbers, letting x be the length of the short base:
a = (x+7) * (x + x+4)/2
66 = (x+7)(x+2)
x^2 + 9x  52 = 0
(x+13)(x4) = 0
x = 4
short base = 4
long base = 8
height = 11
area = 11(8+4)/2 = 11*6 = 66