The triangle is a right triangle with: 1) leg c opposed to angle C. 2) leg b opposed to angle B. 3) hypotenuse, a, opposed to angle A. So, using the definitions of the trigonometric ratios, you get: 1) sin C = opposite leg / hipotenuse = c / a. 2) tan B = opposite leg / adjacent leg = b / c => sin C * tan B = [c / a] * [b / c] = b / a. Answer: b / a