Sine, cosine, and tangent ratios help to identify the angles of a right triangle when the sides are known and vice versa. The sine ratio for this particular problem can be found by dividing the opposite side of B by the hypotenuse.
The opposite side of B is 8
The adjacent side of B is 10
The hypotenuse of the right triangle is 13.
As the sine ratio can be found by dividing the opposite side of B (which is 8), by the hypotenuse (which is 13), the sine ratio for this particular problem is [tex] \frac{8}{13} [/tex]