I need to prove this ∇×(a×b)=a(∇⋅b)+(b⋅∇)a−b(∇⋅a)−(a⋅∇)b
I can work out a x b (I think!) but then I don't know how to take the curl of that and where does the dot product in the answer come from...?
Hi there, a better place for this thread might be here: As for your question: Are you familiar with suffix notation? The left hand side is: ϵijk∇j(a×b)k Expanding out the second cross product and with a few rearrangements, you should be able to obtain the right hand side.