geometry
posted by gayle .
In an isosceles trapezoid, the longest base is 11", a leg is 5", and the height is 4".
Find the length of the shorter base of the trapezoid.

The nonparallel sides of an isosceles
trapezoid are equal and form congruent rt triangles when the altitude is drawn. The base of the rt tiangles can be calculated:
X^2 + Y^2 = Z^2,
X^2 + 4^2 = 5^2,
X^2 + 16 = 25,
X^2 = 25  16,
X^2 = 9,
X = 3.
2X + B2 = B1,
2*3 + B2 = 11,
6 + B2 = 11,
B2 = 11  6,
B2 = 5.