# How do you compute the dot product to find the magnitude of u=20i+25j?

Oct 1, 2016

You do not use the dot-product, to compute the magnitude; you use $| u | = \sqrt{{20}^{2} + {25}^{2}}$

$| u | = \sqrt{1025}$

#### Explanation:

$| u | = \sqrt{{20}^{2} + {25}^{2}}$

$| u | = \sqrt{400 + 625}$

$| u | = \sqrt{1025}$