Vector Addition

Polygonal "Tip to Tail" Method
Consider Mechanical Equilibrium
1. $\sum \vec{F_{i}} = \vec{0}$
2. "Closed force triangle" $\to if \vec{F_{1}} + \vec{F_{2}} + \vec{F_{3}} = \vec{0}$
$\vec{P} + \vec{W} + \vec{R} = 0$