The equal sides of an isosceles trapezoid each measure 5, and its altitude measures 4. If the area of the trapezoid is 48, how do you find the lengths of its bases?

Answer 1

area = average of the bases * altitude

average of the bases = 48 / 4 = 12
... so the sum of the bases is 24

the equal sides and the altitude
... form right triangles at the ends of the longer base
... two 3-4-5 triangles means that the longer base is 6 longer

b + b + 6 = 24 ... 2 b = 18 ... b = 9

so the bases are 9 and 15