ABC is an equilateral triangle with O as its centre `vecF_(1) , vecF_(2)` and `vecF_(3)` represent the sides AB , BC and AC respectively . If the total torque about O is zero then the magnitude of `vecF_(3)` is

Options

A. `F_(1) + F_(2)`
B. `F_(1) - F_(2)`
C. `(F_(1) + F_(2))/(2)`
D. `2 (F_(1) + F_(2))`

Answer

A

Explanation

When a mass is rotating in a plane about a fixed point its angular momentum is directed along a line perpendicular to the plane of rotation .