**The dot product of two parallel vectors is equal to the algebraic multiplication of the magnitudes of both vectors.** If the two vectors are in the same direction, then the dot product is positive. If they are in the opposite direction, then the dot product is negative.

If A and B represent two vectors, then the dot product is obtained by A.B. cos q, where "q" represents the angle between the two vectors. Thus, if the vectors are anti-parallel, q equals 180 degrees; cos 180 equals -1. If the two vectors are parallel, then q equals 0 degrees; cos 0 equals 1.