Khan Academy Static

This more advanced (and very optional) tutorial is fun to look at for enrichment. It builds to figuring out the formula for the area of a triangle inscribed in a circle!

4362_Area_of_inscribed_equilateral_triangle.html

4360_Proof_radius_is_perpendicular_to_a_chord_it_bisects.html

4361_Proof_perpendicular_radius_bisects_chord.html