Cynthia Vaskis

SLM521 Spring 2004

Dropin #3 Assignment

4/6/04

File: dp3dotpr.htm

Taking the Dot product between two vectors produces the cosine of the angle between them if the two vectors are unit vectors. A unit vector of length one in whatever units are being used to measure the length of vectors in your application. To “unitize” a vector see Pythagoras’ theorem (Pythagorean) below. It can be applied in three dimensions to a vector of (x,y,z) instead of in two dimensions.

The Dot Product of two vectors defined as V1 = (x1, y1, z1) and V2 = (x2, y2, z2) is V1*V2 = (x1*x2) + (y1*y2) + (z1*z2) but both V1 and V2 must be unit vectors.