Question

Find the angle between the given vectors to the nearest tenth of a degree.
u = <8, 4>, v = <9, -9>

Answer 1

hint:
use
\(\Large cos(\theta)=\frac{u.v}{||u||~||v||}\)
Note: numerator is dot product.
For an example, see
http://www.wikihow.com/Find-the-Angle-Between-Two-Vectors