# Component of vector a in direction of vector b.

• January 2nd 2012, 08:48 AM
arangu1508
Component of vector a in direction of vector b.
Friends kindly guide me to solve the following problem:

Find the component of 3i-2j+4k in the direction i+j+k.

• January 2nd 2012, 08:59 AM
Plato
Re: vector help
Quote:

Originally Posted by arangu1508
Friends kindly guide me to solve the following problem:
Find the component of 3i-2j+4k in the direction i+j+k.

Be careful, definitions do vary slightly.

If $\mathbf{a}~\&~\mathbf{b}$ are vectors then $\text{comp}_{\mathbf{b}}\mathbf{a}=\frac{\mathbf{a }\cdot\mathbf{b}}{\|\mathbf{b}\|}$.
• January 2nd 2012, 09:19 AM
arangu1508
Re: vector help
Thank you Mr. Plato. Is it projection of a on b ?
• January 2nd 2012, 09:36 AM
Plato
Re: vector help
Quote:

Originally Posted by arangu1508
Thank you Mr. Plato. Is it projection of a on b ?

$\text{proj}_ba=\frac{a\cdot b}{b\cdot b}b$