In law of parallelogram of forces shown in the figure, the expression for magnitude of resultant (R) is given by:
Where, P and Q are forces acting at a point O
α = angle between two forces
1
\(\rm R=\sqrt{P^2+Q^2+2PQ\cos \alpha}\)
2
\(\rm R=\sqrt{P+Q+2PQ\sin \alpha}\)
3
\(\rm R=\sqrt{P+Q+2PQ\cos \alpha}\)
4
\(\rm R=\sqrt{P^2+Q^2+2PQ\sin \alpha}\)