ABC is an equilateral triangle with O as its centre. \(\vec{F_1}\), \(\vec{F_2}\) and \(\vec{F_3}\)represent three forces acting along the sides AB BC and AC respectively. If the total torque about O is zero then the magnitude of F3 is :

\(\frac{F_1 + F_2}{2}\) 2(F1 + F2) F1 + F2 F1 - F2

F1 + F2

∑t = 0 ⇒ (F1 + F2) d = F3d ⇒ F3 = F1 + F2