**THREE DIMENSIONAL FORCE SYSTEMS**

F _{x} =F cos θ _{x}

F _{y} = F cos θ _{y}

F _{z} =F cos θ _{z}

are unit vectors through x, y, and z directions respectively.

θ _{x}, θ _{y}, θ _{z} are the angles made by F with x, y, and z axis respectively (Refer to the vector algebra chapter)