If F→ is the force acting on a particle having position vector r→ and τ→ be the torque of this force about the origin, then
r→.τ→ not equal to zero and F→.τ→ = 0
r→.τ→ > 0 and F→.τ→<0
r→.τ→= 0 and F→.τ→ = 0
r→.τ→ = 0 abd F→.τ→ not equal to zero
Torque is an axial vector, i.e., its direction is always perpendicular to the plane containing vectors r→ and F→.
τ→ = r→ ×F→
Torque is perpendicular to both r→ and F→
τ→.r→ = 0
F→.τ→ = 0