This is really starting to irritate me as I can't seem to get anywhere with it:

I need to solve somthing similar to a trigonometric identity but using the definition of grad,div and curl to verify:

$\displaystyle grad(UV) = U grad(V) + Vgrad(U)$

and..

$\displaystyle grad(F.G) = F(curl G) + G(curl F) + (f.grad) G + (G.grad)F$

I have no idea where to begin, I have the definitions but I fail to see how they can help me, can anybody can help me?