Vector Calculations | Find ⎮v-2w⎮

[MozAngeles]

Homework Statement

If ⎮v⎮=2, ⎮w⎮=3, and the angle between v and w is [tex]\pi/3[\tex], find ⎮v-2w⎮.<br /> <br /> <h2>Homework Equations</h2><br /> <br /> Im not sure how to go about this. maybe use $$\cos\theta[\tex]=u∙v/⎮u⎮⎮v⎮<br /> <br /> <h2>The Attempt at a Solution</h2><br /> i'm not sure where to start. i know this has to be pretty straightforward, but i don't see it...<br /> anyt help would be nice thanks.$$[/tex]

 

[tiny-tim]

Hi MozAngeles!

(write /tex not \tex )

hint: |v - 2w|² = (v - 2w).(v - 2w)