# How do you compute the dot product to find the magnitude of u=<-5,12>?

Jul 10, 2018

$\textcolor{b l u e}{13}$

#### Explanation:

You cannot compute the dot product with only 1 vector. You do not need the dot product to find the magnitude of the given vector anyway.

The magnitude of a position vector $\boldsymbol{a} = \left[{x}_{1} , {y}_{1}\right]$ is given by:

||bba||=sqrt((x_1)^2+(y_1)^2

Hence:

$\boldsymbol{u} = \left[- 5 , 12\right]$

$| | \boldsymbol{u} | | = \sqrt{{\left(- 5\right)}^{2} + {\left(12\right)}^{2}} = \sqrt{169} = 13$