Archimedes method for lower bound of pi with inscribed regular polygons. Move the slider to go from 6 to 12 to 24 to 48 to 96 sides. Click the two checkboxes to see the method of bisecting angle BCD and using the angle bisector theorem, similar triangles, and the pythagorean theorem to get the side of the next figure.
If BC, DC, and BD are known, the angle bisector theorem can be used to find BG and GD. Then with similar triangles GBH and GCD, BH can be found.