I'm not sure if this is the right place to put this?
Show that: curl(fu) = fcurlu + (gradf) x u
By using this in relation to Stoke's theorum, show that for a simple closed curve C,
(Line integral) fdS = -(surface integral) (gradf) x dS
Firstly, is this a typo? I've never heard of a line integral of a function wrt to surface element?
I think Stoke's Theorum is:
(Line integral)(A.dl) = (surface integral)((curlA).dS)
I did the first part fine. I then tried to do
(surface integral) (gradf)xdS = (surface integral) (curl(fdS) - fcurldS)
I then got stuck. Please help!