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Properties of the Cross Product

The easy calculations above can be combined with the properties of the cross product below to calculate the cross product of two general vectors.

For any vectors, tex2html_wrap_inline677 , tex2html_wrap_inline679 , and tex2html_wrap_inline815 and scalar tex2html_wrap_inline817 :

  1. tex2html_wrap_inline819 .
  2. tex2html_wrap_inline821 .
  3. tex2html_wrap_inline823 .

Now we can construct a general formula for the cross product of two vectors:

equation369

This formula for the cross product is rather long, but notice that the tex2html_wrap_inline635 component of the cross product of tex2html_wrap_inline585 and tex2html_wrap_inline521 does not involve the tex2html_wrap_inline635 component of either vector. There is an easier way to remember the cross product. It can be written in matrix notation as

eqnarray381

If you are familiar with matrix calculations, you should recognize this as the determinant of a three-by-three matrix. It should also be noted that, while all other vector operations are defined for vectors in any number of dimensions, the cross product is only defined for three dimensional vectors.

As an example, let's compute the cross product of the vectors tex2html_wrap_inline833 and tex2html_wrap_inline835 :

eqnarray414



Vector Calculus
Mon Jul 14 10:10:30 MST 1997