# Thread: Help with Umbilical Points

1. ## Help with Umbilical Points

If P is an umbilical point then the second fundamental form is constant

Thanks!

2. ## Re: Help with Umbilical Points

What is the link between the second fundamental form and the normal curvature?

3. ## Re: Help with Umbilical Points

k_n = II(X,X) and k_n is constant. But I need that II(X,Y) constant. or am I wrong?

4. ## Re: Help with Umbilical Points

Originally Posted by kezman
k_n = II(X,X) and k_n is constant. But I need that II(X,Y) constant.
Use the bi-linearity.

5. ## Re: Help with Umbilical Points

kn=II(X,X) =???= II(X,Y). I need something in between to reach the right side????