The two vectors (say A and B) of different magnitudes cannot be combined to give zero resultant since minimum value of combination is ІA-BІ which is not zero if AB.

The three vectors A, B and C of different magnitudes can be zero such that they form a closed triangle, then,

      A+B+C=0

or, C=-(A+B)

Hence, the sum of three vectors may be zero if vector sum of any two vectors is equal and opposite to the third vector.

Note: The vectors can give this result only if...

conceptualizing the truth,in hegel's term. A lot of philosophers(like descartes' three kinds of ideas) in his time (and a lot of mindfulness practitioners these days)believed a higher form of truth(or knowledge) exists which cannot be articulated but is to be intuited and felt.Hegel didnt consider this to be scientific.you can never know if your intuition is true or its just you making the stuff up.

Sigma bond is stronger than Pi bond because of the following reasons:

1. The extent of overlapping in Sigma bond is greater than in Pi bond.
2. The electron density in intermolecular axis is more in Sigma bond than in Pi bond.
3. There is free rotation of atom about Sigma bond but not about Pi bond.