Calculus: Find Gradient of θ Without Differentials of Arccos

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SUMMARY

The discussion focuses on finding the gradient of the angle θ defined by the expression cosθ = (a·b)/(ab) without using differentials of arccos. The user specifically seeks methods applicable for angles between 60 and 100 degrees, ruling out small angle approximations. Participants confirm the objective is to compute ∇rθ, emphasizing the need for alternative approaches to traditional calculus methods.

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  • Basic concepts of multivariable calculus
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raintrek
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Homework Statement



I have the following expression:

cos\theta = \frac{\vec{a}\cdot \vec{b}}{ab}
(this is simply taken from a dot product rule for two vectors)

However I need to find \nabla_{\vec{r}i} \theta

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!
 
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Please confirm: You want to find the gradient of theta?
 
It's ok, I read the question wrong. Sorry about that folks
 

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