# Seeking help on vector calculus

1. Jun 27, 2006

### boarie

Dear all

I'm a newbie here...having some prob and hope to have your expert advice on how to solve the equation attached.

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2. Jun 27, 2006

### J77

Do you want a general solution, or have you been given, eg., m=(m1,m2,m3), r=(r1,r2,r3), or have you specific values for the vectors m and r?

Either way, do the cross product first, then divide by the scalar magnitude, then apply the curl function.

3. Jun 27, 2006

### boarie

hi J77

In fact, the solution to the above is given as attached... I can't seem to derive to the stated form...

Would really appreciate if any guru can shed some light...

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4. Jun 28, 2006

### J77

Quick reply, but to me the transformation seems to lie in using Lagrange's formula:

$$a\times(b\times c)=b(a\cdot c)-c(a\cdot b)$$

ie. "BAC minus CAB"