These laws have been already defined in articles 1.1.4 and 1.1.5 respectively (see page 2 and 4). Parallelogram law of forces states that, “If two forces acting at a point be represented in magnitude and direction by the two adjacent sides of a parallelogram, then their resultant is represented in magnitude and direction by the diagonal of the parallelogram passing through that point.

Triangle law of forces states that, if three forces acting at a point be represented in magnitude and direction be the three sides of the triangle taken in order, they will be in equilibrium ?