Cyclic Quadrilaterals
Definition:
A cyclic quadrilateral, by definition, is any quadrilateral that can be inscribed inside a circle. That is, all 4 vertices of a cyclic quadrilateral always lie on the circle itself.
Mess around with the applet for a couple of minutes, and then answer the questions that follow.
Q1: What can you say about opposite angles in a cyclic quadrilateral?
Q2: What can you say about the sum of the interior angles of a cyclic quadrilateral? (i.e. the sum of the red, green, blue and orange angles)