# Math Help - Component of vector a in direction of vector b.

1. ## 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.

2. ## Re: vector help

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 $\text{comp}_{\mathbf{b}}\mathbf{a}=\frac{\mathbf{a }\cdot\mathbf{b}}{\|\mathbf{b}\|}$.

3. ## Re: vector help

Thank you Mr. Plato. Is it projection of a on b ?

4. ## Re: vector help

Originally Posted by arangu1508
Thank you Mr. Plato. Is it projection of a on b ?
$\text{proj}_ba=\frac{a\cdot b}{b\cdot b}b$