O' is the centre of a square ABCD. F_(1),F_(2),F_(3) and F_(4) are four forces acting along sides AB, BC, CD and AD as shown in figure. What should be the maginitude of F_(4) so that, the total torque about 'O' is zero ?

O' is the centre of a square ABCD. F_(1),F_(2),F_(3) and F_(4) are fou

1.	O' is the centre of a square ABCD. F_(1),F_(2),F_(3) and F_(4) are four forces acting along sides AB, BC, CD and AD as shown in figure. What should be the maginitude of F_(4) so that, the total torque about 'O' is zero ?
Answer» `F_(1)+F_(2)+F_(3)` `F_(1)+F_(2)-F_(3)` `F_(1)-F_(2)-F_(3)` `(F_(1)+F_(2)+F_(3))/(2)` ANSWER :A