Play around with the radius and also the three points to observe the angles as the radius gets bigger? (1)
What do you recognize about the angles as the radius grows and shrinks?
While observing the changing circumference(2), what do you notice?
Compare the different circles (difference in the radius is a different circle). What are some similarities and differences?
What do you notice when you add up all of the angles of each of the different circles? What are the angles equal to?

Hints:
1.) It would be easier to observe if you only play with one variable at a time.
2.) Circumference equation is 2*(PI)*r.