How do you find the height of a trapezoid?

How do I find the measurement of an unknown base of a trapezoid if I don't have the area or the height?

• I have the measurements of three sides of a trapezoid. My base is 4in. and my legs are 5in. I need the measurement of the other longer base. I know the angles of the one base are 85* ...show more

• Answer:

  The two heights of the trapizoid forms a rectangle in the middle. The sides form the hypotenuse of a right triangle with the height. So form two triangles with h and hypotenuse. One triangle forms an 85, 5, 90 degree triangle, the other forms a the same triangle but upside down. 95 degrees is -5 degrees on the Cartesian plane. When you piece the triangles together you actually get a parallelogram. Since one base is 4, this is the base with the upside down triangle with the vertex on the corner. The other base then 4 too. You get the base lengths without calculation but by construction.