Recent content by AlmostSwedish

Thanks man. If I knew were you live I'd send you a box of cookies.

Quick question, if I take the derivative with respect to an element of r1, e.g x1, instead of r1, do I still have to rewrite the expression?

That makes a lot of sense, though I'm starting to suspect that I missinterpreted the problem to begin with. Thanks a lot!

Homework Statement Find the partial derivative with regards to vector r1 for the expression: theta = acos \frac{((r1-r2).(r3-r2))}{||r1-r2||*||r3-r2||} where "." is the dot product r1,r2 and r3 are positions in 3D-space. The expression above comes from the definition of the dot product...

Thanks for your reply. I don't really see why I would want move the cosine to the left side since I want an expression for the derivatives of just theta anyway. The main problem that I've had is that I don't know how to differentiate a dot product, so if you could just show a quick example...

No the derivatives I'm tying to find are: \frac{d \theta}{dr1} \frac{d \theta}{dr2} \frac{d \theta}{dr3} I'm sorry I didn't make myself clear in the original post. I used the " ' " just for convinience.

Homework Statement Ok, so I need to differentiate the following theta = arccos(((r1-r2).(r3-r2))/(||r1-r2||*||r3-r2||)) With regards to r1, r2 and r3 r1, r2 and r3 are three dimensional vectors. "." is the scalar/dot product and * is ordinary multiplication.Homework Equations Definition of...