What are minmum number or unequal fores whose vector sum is zero ?

The minimum number of unequal forces that can have zero resultant is

(A): The minimum number of coplanar vectors whose sum can be zero is three. (R): The three vectors must be coplanar to produce equilibrium.

What are the minimum number of forces (all numerically equal) whose vector sum can be zero ?

What is the angle between two vectors whose vector product is zero ?

Minimum number of two coplanar vectors of equal magnitude whose vectors sum could be zero, is: