Oh I was trying to figure out what you meant by that, but I see you changed your suggestion. It's a real head scratcher, of all the stuff I've done with vectors, this question should work out the way I did it but nothing seems to yield a realistic result.
Homework Statement
vector A = 3U-V
vector B = U+2V
U and V are vectors
|U| = 3|V|
Given that vector A and vector B are perpendicular vectors, find the angle between vector U and vector V.
Homework Equations
A*B = |A||B|cos(∠AB)
A*A = |A|^2
The Attempt at a Solution
Since A and B are...