Proof Without Words

Drag the points in the sketch below.[br]What do you notice? What does this prove? How does this prove it?

What are your thoughts on GeoGebra?

I can't see it being useful in my class. I am still in summer mode...ask me later! Love it! Can't wait to use it. I needs some more time to experiment. I like another similar program better.

Information: Proof Without Words