Fig 2Forces are vectorssize and direction|F| = √(Fx² + Fy²)
A force has a size and a direction, so forces add like arrows, not like numbers. To add two, put the tail of the second on the tip of the first. The sum runs from the first tail to the last tip. To work with one, split it into perpendicular components with cos and sin. Then you can add all the x parts and all the y parts as ordinary numbers, and rebuild the result with Pythagoras: |F| = √(Fx² + Fy²).