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# Vector Multiplication Reminder

Module by: Paul Padley. E-mail the author

Summary: A three minute reminder of vector multiplication.

It is presumed that you are familiar with vector multiplication.

Here are some questions to ask yourself as a refresher:

A B A B . Is it a vector or a scalar?

Answer: scalar A B = A x B x + A y B y + A z B z A B = A x B x + A y B y + A z B z

A × B A × B . Is it a vector or a scalar?

Answer: Vector ( A × B ) x = A y B z A z B y ( A × B ) y = A z B x A x B z ( A × B ) z = A x B y A y B x ( A × B ) x = A y B z A z B y ( A × B ) y = A z B x A x B z ( A × B ) z = A x B y A y B x

What is A × A A × A

What is A ( A × B ) A ( A × B )

Another useful thing to remember A ( B × C ) = ( A × B ) C A ( B × C ) = ( A × B ) C = ( C × A ) B = ( C × A ) B This is the scalar triple product which is the volume of a parallelopiped whose edges are given by A , B , C A , B , C .

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