# I feel so guilty

**URL:** <https://forum.kirupa.com/t/i-feel-so-guilty/175496>\
**Category:** random\
**Created:** [January 15, 2006, 5:05am UTC](https://forum.kirupa.com/t/i-feel-so-guilty/175496 "2006-01-15T05:05:06Z")\
**Posts on this page:** 1\
**Page:** 1

<div class="post-metadata">

**Author:** ![MTsoul](https://avatars.discourse-cdn.com/v4/letter/m/91b2a8/32.png) [@MTsoul](https://forum.kirupa.com/u/MTsoul)\
**Post date:** [January 15, 2006, 5:05am UTC](https://forum.kirupa.com/t/i-feel-so-guilty/175496/1 "2006-01-15T05:05:06Z")

</div>

## asking help for math homework ☹

Suppose that the vectors **V** [SIZE=-1]1[/SIZE], **V** [SIZE=-1]2[/SIZE], and **V** [SIZE=-1]3[/SIZE] satisfy the following:

**V** [SIZE=-1]1[/SIZE] + **V** [SIZE=-1]2[/SIZE] + **V** [SIZE=-1]3[/SIZE] = **0**  
**V** [SIZE=-1]1[/SIZE] • **V** [SIZE=-1]2[/SIZE] = **0**  
|| **V** [SIZE=-1]1[/SIZE]|| = 66  
|| **V** [SIZE=-1]2[/SIZE]|| = 73

## What is the length || **V** [SIZE=-1]3[/SIZE]||?

||v|| is the absolute length of a vector. I just can’t figure out the algebra. I laid out everything, and it just won’t solve by itself. Help?