In this clip the teacher leads a discussion about reference angles.
Motion of Fly Applet , Clip 1, Determining Domain and Range, 3:25
The teacher discusses the range of sine to help students realize the domain is -1 to 1 quickly.
Hhe uses the applet to allow the students to make sense of the range for the inverse trig functions. To help the students create their explanation he uses the diagram on the overhead.
He uses this range to discuss what the students should expect for an output when they use arccos. This is followed by a similar discussion for arcsin.