cos (A-B) = cosA cosB - sinA sinB
Note that cosA = 4/5 and sin B = 7/25, which you can prove using
cos^2 x + sin^2 x = 1
If sin A=3/5 and cosB = 24/25 and angle A and angle B are both in quandrant 1. What is sthe exact value of cos (A-B)?
2 answers
117/125