# Seeking help on vector calculus

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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• equ6-27-2006-3.47.09 PM.jpg
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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.

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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• equation6-27-2006-10.16.32 PM.jpg
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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"