#### opus

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It gives me the cosine piece: $$\cos(\vec A, \vec B) = \frac{\vec A ⋅\vec B}{|A||B|}$$ which I assume is just from the dot product, but it has no derivation of this, and doesnt mention it for sine.

I've looked around Google for derivations of this, but only find worked examples of problems like the one I have given. Could anyone reference me to the derivations for these?