 |
Encyclopedia—vectorAddition and Multiplication of VectorsThe addition, or composition, of two vectors can be accomplished either algebraically or graphically. For example, to add the two vectors U [-3,1] and V [5,2], one can add their corresponding components to find the resultant vector R [2,3], or one can graph U and V on a set of coordinate axes and complete the parallelogram formed with U and V as adjacent sides to obtain R as the diagonal from the common vertex of U and V. Two different kinds of multiplication are defined for vectors in three dimensions. The scalar, or dot, product of two vectors, A and B, is a scalar, or quantity that has a magnitude but no direction, rather than a vector, and is equal to the product of the magnitudes of A and B and the cosine of the angle θ between them, or A ⋅ B = |A| |B| cos θ. The vector, or cross, product of A and B is a vector, A × B, whose magnitude is equal to |A| |B| sin θ and whose orientation is perpendicular to both A and B and pointing in the direction in which a right-hand screw would advance if turned from A to B through the angle θ. The vector product is an example of a kind of multiplication that does not follow the commutative law, since A × B = -B × A. Sections in this article: The Columbia Electronic Encyclopedia, 6th ed. Copyright © 2007, Columbia University Press. All rights reserved.
|
|
