According to Varignon’s theorem, the algebraic sum of several concurrent forces about any point is equal to the moments of their resultant about the point. To prove Varignon’s Theorem, consider the force R acting in the plane of the body as shown in the above-left-side…

In statics, Lami’s theorem is an equation that relates the magnitudes of three coplanar, concurrent, and non-collinear forces that keep a body in static equilibrium. Lami’s theorem states that if three forces acting at a point are in equilibrium, each force is propo…