Answer: 15/17
=========================================================
Explanation:
A drawing may help. See the image below.
Angle X is the 90 degree angle, so angles W and W are the acute angles of right triangle VWX.
The reference angle here is W. Since this is the reference angle, the side opposite angle W is VX = 15. We simply call this "opposite".
The hypotenuse is always opposite the 90 degree angle. This is true no matter what acute reference angle you pick. Since X = 90, this makes WV = 17 the opposite side. Also, the hypotenuse is always the longest side.
The sine of an angle is the ratio of the opposite and hypotenuse
sin(angle) = opposite/hypotenuse
sin(W) = VX/WV
sin(W) = 15/17
Side note: The side XW = 8 isn't used at all. If you wanted to compute cos(W) or tan(W), then you would use side XW.
