Question

State and prove the "Lamis's Theory"

Answer 1

Statement: Lami's Theorem states, “When three forces acting at a point are in equilibrium, then each force is proportional to the sine of the angle between the other two forces”.

Propf: According to Lami’s theorem statement, we will have following equation as mentioned here.  

                                     A α Sin α, A = K Sin α

                                     B α Sin β, A = K Sin β

                                     C α Sin γ, A = K Sin γ  

Or we can also redefine it as  

                           K = A/ Sin α = B/ Sin β = C/ Sin γ

Therefore, according to Lami’s theorem statement, we will have following equation which could be used in order to secure the magnitude of the unknown force in a case where object will be exerted by three coplanar, concurrent and non-collinear forces and object or body is in equilibrium.