[SOLVED] Determining if one vector is perpendicular to another.

If the vectors u, v and w in R3 are given by:

....**[ 1]**....**[-2]**....**[-2]**

**U = [-1] V =[ 3] W =[ 1]**

....**[ 3]**....**[ 1]**....**[ 1]**

determine which (if any) of the following statements are true:

(i) u is perpendicular to v.

(ii) u is perpendicular to w.

(iii) v is perpendicular to w.

This is a sample question from an exam I had recently. Im not to interested in the answer. More interested in the technique and formulas used.

Apologies for the periods.

Any help is greatly appreciated.