Find the Exact Value of Sin(A-B) Given Information About Angle A and Angle B (Without a Calculator)

Given cosA=-5/13 and angle A is in QII, and tanB=15/8 and B is in QIII, find the exact value of sin(A-B). Each angle is drawn in standard position and the values for x, y, and r are found for each angle. From this information the exact values of the sine and cosine of each angle are found and they are used in the formula for sin(A - B).

Timestamps
0:00 Introduction
1:12 Find x, y, and r for angle A
2:55 Find x, y, and r for angle B
5:18 Find sin(A-B)