forces of friction with angles

[Tubbles]

I know the formula for friction coefficients is force over weight, but i dont understand what to do when angles are involved. Please help me by showing me where to put the angle measurements in this problem.

A 1000-N crate is being pushed across a level floor at a constant speed by a force F of 300N at an angle of 20 degrees below the horizontal. What is the coefficent of kinetic friction between the crate and the floor?

[antiflag403]

your going to use vector addition. you must find the force in its components. (x and y). You can use this using simple trig laws. it helps to draw a free body diagram. good luck!