The measure of one of the smaller base angles of an isosceles trapezoid is 60 degrees. The shorter base is 5 inches long and the altitude is 3 sqrt 3 inches long. What is the number of inches in the perimeter of the trapezoid?
sin 60 = altitude / side length
side length = alltitude / sin 60 = ( 3sqrt 3) / [ sqrt 3 / 2 ] = 6
The longer base is found as
5 + 2a
Where a = 6/2 = 3
So the longer base = 11
So the perimeter = 5 + 11 + 2*6 = 28
See the image below :
