Question

15. If sin A = 5/13 and sin B = 4/5 then the value of cos (A - B) is
(1) 65/56
(2) 56/65
(3) 16/65
(4) - 16/65​

Answer 1

Answer:

If A, B belong to Quadrant 1

sin A = 5/13. cos A = 12/13

sin B = 4/5. cos B = 3/5

cos (A-B) = cos A cos B - sin A sin B

= 36/65+20/65

=56/65

option (2) is correct