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#### Petrus

##### Well-known member

- Feb 21, 2013

- 739

This is an old exam.

In top of the exam paper it says. Evrything is on Orthogonal-System

Vector \(\displaystyle u\) got the length \(\displaystyle 3\), vector \(\displaystyle v\) got the length \(\displaystyle 2\) and vector u-v got the length \(\displaystyle \sqrt{7}\)

(a) calculate length of vector \(\displaystyle u+v\)

(b) calculate the angle between \(\displaystyle u\) and \(\displaystyle v\)

I did not understand how you do (a) and for (b) I got confused cause if it's orthogonal System then the angle will be \(\displaystyle \frac{\pi}{2}\) but that is wrong. So I assume we don't got orthogonal system in this one?

Regards,

\(\displaystyle |\pi\rangle\)