We will have that an equation that would describe such an scenario could be given by:
Here "a" represents the magenitude of the "main" force in the scenario, and "f" represents the magnitude of the friction force in the scenario. The reason these magnitudes are multiplied by cosine and sine is that they are the component forces of a vector. And the reason they are all under a radical is that the final force is the vector formed by the component forces, and this can be graphicaly represented and understood as a right triangle.