Area of a Trapezoid (3)

Points A, B, C, D are vertices of the trapezoid below. Move these points anywhere you'd like.

Now slowly slide the slider (at the bottom) all the way to the right. What do you notice? What do you wonder?

In general, how can we find the area of a trapezoid? Describe from what you see here. (Feel free to reposition A, B, C, and D to explore various types of trapezoids).

Quick silent demo: