i apologise if this is the incorrect forum, i assume it would go under here or perhaps calculus forum - vector help!

http://upload.wikimedia.org/wikivers...ectorCross.png

find the formula for $\displaystyle ||b -a||^2$ in terms of $\displaystyle ||b||^2$, $\displaystyle ||a||^2$ and $\displaystyle b·a$

thankyou so much in advance!