Answer: D
Step-by-step explanation: By using SOH for sin A, 'S' being sin, 'O' being opposite side of angle A and 'H' being the hypotenuse which is the longest part of the triangle you would find that 15 is opposite from Sin A and 17 the hypotenuse, 15/17.
For cos A you would use CAH, C= cos, A which is the adjacent of the triangle located next to angel A which is 8, and H= hypotenuse (also note that the hypotenuse never changes even if the angle may be different) CAH would be cos A = 8/17