(1) Where a touches the circle on either end.
(2) The center of a
(3) The center of the circle
The angle at (1) is obviously 30 degrees. Simple trigonometry will show the sides to be of lenths 1, 1/2, and sqr(3)/2. From here it can be seen that a=1/2 and b=sqr(3).
Michael Shackleford, ASA - June 25, 2000