(adsbygoogle = window.adsbygoogle || []).push({}); First question:

a x b = -b x a

Why is this so?

As I understand, a major purpose of the cross product (if not,thepurpose) is to find a third vector that is perpendicular to two other vectors simultaneously. Let's say a x b = c. Shouldn't the answer really be, a x b = +/- c? Since, of course, both c and -c are perpendicular to a and b simultaneously.

The situation of the sqrt(4) = +/- 2 is analogous to this.

Second question:

The cross product is said to be something that only works in 3 dimensional space. In 2D, it is said to be not applicable. Take two vectors in 2D that are just the negative of each other. Obviously a line can be drawn straight up relative to these two vectors that is perpendicular to both (visualize an upside down T). Since the cross product's main purpose is to find a third vector that is perpendicular to two other vectors, can it be said that the cross product fails in 2 dimensional space?

Thanks for your time.

**Physics Forums | Science Articles, Homework Help, Discussion**

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Questions on Cross Product

Loading...

Similar Threads for Questions Cross Product |
---|

I Divergent series question |

B Function rules question |

B Question about a limit definition |

A Angular Moment Operator Vector Identity Question |

I A question regarding Logistic population model |

**Physics Forums | Science Articles, Homework Help, Discussion**