Proving Law of Sines Using Vector Cross Product

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Homework Statement


Prove the law of sines using a vector cross product. (Hint, consider the area of the triangle and that A+B+C=0.)


Homework Equations


|A||C|sin ( θ ) = (a2c3 − a3c2) + (a3c1 − a1c3) + (a1c2 − a2c1)


The Attempt at a Solution


The farthest I went is to show .5 |a||c|sin \theta .. I've tried some other things but then it just turns out to be some incomprehensible mess. I chose C to be my longest side. I simply do not know what to do; I've exhausted both forms of the cross product I know, and it appers to go nowhere.
 
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Never mind, I figured it out. Thanks anyway!
 
There are two things I don't understand about this problem. First, when finding the nth root of a number, there should in theory be n solutions. However, the formula produces n+1 roots. Here is how. The first root is simply ##\left(r\right)^{\left(\frac{1}{n}\right)}##. Then you multiply this first root by n additional expressions given by the formula, as you go through k=0,1,...n-1. So you end up with n+1 roots, which cannot be correct. Let me illustrate what I mean. For this...
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