## Proofs Without Words

These visual examples of geometry ideas are sometimes called Proof Without Words.

- Try this one. It shows a conclusion about the sum of the three interior angles of any triangle by folding down the corners of the triangle. Ingenious!

- Next, try this one. It shows the same conclusion about the sum of the three interior angles of any triangle in a different way. Grab a vertex, move it around, and watch what happens.

- How about the sum of the exterior angles of a polygon? Go here. This is an amazing way to show a powerful conclusion in geometry. If you wish add a side to the polygon by using a Command click on a Mac. Beautiful!
- How about a proof for the Quadrilateral? Or Pentagon? Or even a Hexagon? Go here. (You may want to scroll down the page some).

Look at the visual proof of the Pythagorean Theorem using a dissection method.

One more proof of the Pythagorean theorem, this time using WATER!

One more proof of the Pythagorean theorem, this time using WATER!

Area of a Rectangle (animated)

Area of a Parallelogram (animated)

Area of a Triangle (animated)

Area of a Trapezoid (animated)

Area of a Circle (animated)

Area of a Parallelogram (animated)

Area of a Triangle (animated)

Area of a Trapezoid (animated)

Area of a Circle (animated)