Area of a Trapezoid

Compare the parallelogram ABCD and the trapezoid EFGH. Grab and move the point B to change the base of the parallelogram. Grab and move the point D to change the height of the parallelogram. Grab the point F to change the bases of the trapezoid. Use the rotation slider to rotate the trapezoid clockwise around the point O. What conclusion can you make about the area of a trapezoid when it has the same height as a parallelogram and when the sum of its bases is equal to the base of the parallelogram? Verify your conjecture by using the translation slider.