# Homework Help: Multivariable Calculus - Parallelogram

1. Sep 11, 2010

### Larrytsai

1. The problem statement, all variables and given/known data

Suppose u=(-2,-10) and v=(-2,-2) are two vectors that form the sides of a parallelogram. Then the lengths of the two diagonals of the parallelogram are...

2. Relevant equations

3. The attempt at a solution
I tried using pythagrean theorem and some trig to find the angles, then i thot finding the internal angle of the paralellogram i can divide it by 2 and find half of the diagonal then multiply it by 2. The angle i found was 16.85 degrees. with that i would use
cos(16.85)*sqrt(104) to find half of the length of the diagonal.
Am i on the right track?