- #1
raintrek
- 75
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Homework Statement
I have the following expression:
[tex]cos\theta = \frac{\vec{a}\cdot \vec{b}}{ab}[/tex]
(this is simply taken from a dot product rule for two vectors)
However I need to find [tex]\nabla_{\vec{r}i} \theta[/tex]
Is there a way I can do it without involving differentials of arccos and the like? I can't use a small angle approximation as these angles are around 60-100 degrees. Any suggestions appreciated!