# Spatial vectors

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• June 19th 2012, 01:07 AM
whyyie
Spatial vectors
Let $\vec{a}$ and $\vec{a}$ be 3d vectors.

Explain in words with the aid of a diagram why:
( $\vec{a}$x $\vec{b}$). $\vec{b}$ = 0.

Explain with the aid of a diagram, that if
$\vec{b}$x( $\vec{a}$. $\vec{b}$) = $\vec{a}$,
what is $\vec{a}$. $\vec{b}$?

should be using right hand rules etc
• June 19th 2012, 05:47 AM
Reckoner
Re: Spatial vectors
Quote:

Originally Posted by whyyie
Explain in words with the aid of a diagram why:
( $\vec{a}$x $\vec{b}$). $\vec{b}$ = 0.

Explain with the aid of a diagram, that if
$\vec{b}$x( $\vec{a}$. $\vec{b}$) = $\vec{a}$,
what is $\vec{a}$. $\vec{b}$?

These should be easy to answer if you set up a diagram.

What do we know, geometrically, about the cross product of two vectors? And when will the dot product of two vectors be zero?