How do I solve for the opposite leg of an angle using Cosine?

To help you get a picture for it draw a right triangle. The right angle is on the bottom left and the angle on the top is 50�, the hypotenuse is 0.9. the Adjancent leg is not given but the problem is asking for the measurement of X which is on the opposite leg from angle 50�. The problem instructs me to use the cosine table. So how do I go about solving this? (The answer for X needs to be in decimal form and rounded to the nearest tenth.