# How do you find the sum of the unit vectors (9,7,-11) and (7,3,-2)?

Dec 7, 2016

$< \frac{9}{\sqrt{251}} + \frac{7}{\sqrt{62}} , \frac{7}{\sqrt{251}} + \frac{3}{\sqrt{62}} , - \frac{11}{\sqrt{251}} - \frac{2}{\sqrt{62}} >$

#### Explanation:

Unit vector in the direction of the vector $a$ is $\frac{1}{|} a | a$.

So, the um of the unit vectors here is

$\frac{1}{\sqrt{{9}^{2} + {7}^{2} + {\left(- 11\right)}^{2}}} < 9 , 7 , - 11 >$

$+ \frac{1}{\sqrt{{7}^{2} + {3}^{2} + {\left(- 2\right)}^{2}}} < 7 , 3 , - 2 >$

$= < \frac{9}{\sqrt{251}} + \frac{7}{\sqrt{62}} , \frac{7}{\sqrt{251}} + \frac{3}{\sqrt{62}} , - \frac{11}{\sqrt{251}} - \frac{2}{\sqrt{62}} >$