SOLUTION: Find the exact value, given that sin A= -4/5, with A in quadrant IV, tan B= 7/24 with B in quadrant III, and cos C= -5/13 with C in quadrant II. cos2A I have tried doing it bu

Algebra ->  Trigonometry-basics -> SOLUTION: Find the exact value, given that sin A= -4/5, with A in quadrant IV, tan B= 7/24 with B in quadrant III, and cos C= -5/13 with C in quadrant II. cos2A I have tried doing it bu      Log On


   



Question 923528: Find the exact value, given that sin A= -4/5, with A in quadrant IV, tan B= 7/24 with B in quadrant III, and cos C= -5/13 with C in quadrant II.
cos2A
I have tried doing it but i end up with cos25/169-sin16/25. I'm not sure that it is correct.

Answer by ewatrrr(24785) About Me  (Show Source):
You can put this solution on YOUR website!
sin A= -4/5 (quadrant IV) cos A = 3/5 sqrt%285%5E2+-+4%5E2%29+=+3
cos2A = cos^2A - sin^2 A = (3/5)^2 - (-4/5)^2
........
tan B= 7/24 with B in quadrant III, sqrt%287%5E2+%2B+24%5E2%29+=+25
sin B = -7/25, cos B = -24/25
.......
cos C= -5/13 with C in quadrant II. , sin C = 12/13 sqrt%2813%5E2+-+5%5E2%29+=+12