Question 1162379
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5-12-13 and 3-4-5 are Pythagorean Triples.<br>
Given cosA = -5/12, sinA is 12/13 or -12/13, depending on the quadrant.<br>
Given sinB = 3/5, cosB is 4/5 or -4/5, depending on the quadrant.<br>
After you find sinA and cosB, use the formulas you show to find sin(A-B) and cos(A-B).<br>
Then tan(A-B) is just sin(A-B) divided by cos(A-B).<br>