Let A, B, and C be points on a circle of radius 18. If angle ACB = 90 degrees, what is the circumference of the minor arc {AB}? Express your answer in terms of pi.
If ACB = 90°, then A,B are endpoints of the diameter
Then ACB is an inscribed angle and its intercepted arc = 2*90 =180°
So....the arc length that it intercepts is just a semi-circle with a radius of 18/2 =9
The arc length = 9pi
