1. What is the relationship among inscribed angles and their intercepted arcs? Central angles and their intercepted arcs have what relationship? For a diameter, what is the measure of the intercepted arc? What is the measure of an angle formed by a tangent line and a radius or diameter?

2. How do you prove the angles opposite each other in an inscribed quadrilateral add up to 180 - note: we are looking for the proof, not the rule - the rule says they add to 180, how can you prove this is true?