Yes. If the resultant of any two vectors is equal in magnitude but opposite in direction to the third vector i.e. $A+B=-C,$ then the resultant of the three vectors will be zero i.e. $A+B+C=0.$

However, this will only happen if the three vectors are coplanar i.e. they lie in the same plane. If they are not coplanar, then the resultant of two vectors will not be directed towards the third vector. Hence, they cannot cancel each other.

[**Read:** Triangle Law of Vector Addition]