When a load is resting on an inclined plane, there is a force mg sin(x) that is vertical to the inclined plane and a force mg cos(x) that is horizontal to the plane acting on it. My textbook says the weight mg has two components: mg sin(x) and mg cos(x). But when adding up mg sin(x) to mg cos(x), it does not equal mg. If mg and N are the only forces in this system, which means the net force should be 0, how should I explain the existence of mg sin(x) and mg cos(x)? Do mg sin(x) and mg cos(x) have their own reaction force to cancel them out and turn the net force to be 0 too, or is it wrong to say that the system's net force is 0? And how are the formulas mg sin(x) and mg cos(x) that are used to describe these two forces derived?