Thread: vector calculus finding the surface normal

okay i was reading the book "div, grad cur and all that"
i've just started for my exam. but i got stuck in the beginning. i'm attaching the page cuz i really dont get it .
basically pages 14 and 15. i dont get how they calculate the components of u and v.
if someone explains u i'll get v obviously.
thanks

Simple :-

Write the surface in parametric form i.e then find partial derivative of this parameteric representation with respect to and which will give you and .

Then their cross product will give the Normal to the surface,

x