Hi everyone, new here and trying to calculate the mean curvature for the following surface:

r(u,v)=ui+f(u)cos(v)j+f(u)sin(v)kI have been through the process of finding tangent vectors and a unit normal vector to the surface, so up to the point where I have had to substitute 6 scalars into:

h(p)=

aG-2bF-cE2(EG-F

^{2})

The only problem I seem to be having is not being able to simplify it... This is what I have:

h(p)=

±f''(u)f(u)^{2}-f'(u)^{2}-1

2f(u)(1+f'(u)^{2})√(cos^{2}(2v)f'(u)+1)

Maybe missing something really simple here or I have made a mistake in calculating the scalars.

Any help, much appreciated!