Vector Quantities – Vector quantities have both magnitude and direction and unless they acting in the same straight line cannot be directly summed. Velocity, acceleration and momentum are typical vector quantities. Vector quantities can be combined to form a resultant vector by the use of the parallelogram of vectors. Two adjacent sides of a parallelogram can represent two vectors (the direction by the angle between them and their magnitude by their length); the diagonal of the parallelogram drawn through the point at which the two sides meet represents the resultant single vector.

Further Information on this Topic can be found in the books of R.P.W. Scott by following the listed links