# Homework Help: Differential Geometry

1. Nov 17, 2013

### metzky

1. The problem statement, all variables and given/known data
Using the curve $\vec{a}$(u,v)= (u,v,uv) for all (u,v) ε R^2

Find the matrix for d$\vec{N}$ in the basis of {$\vec{a}$$_{u}$,$\vec{a}$$_{v}$}
2. Relevant equations
Well first off i found the partial derivatives
$\vec{a}$$_{u}$ which is 1,0,v, while $\vec{a}$$_{v}$ is 0,1,u
Then using those i found the normal vector which i calculated as $1/\sqrt{v^{2}+u^{2}+1}$ (-v,-u,1)

3. The attempt at a solutionNow this is where i get lost. Our book does not explain this very well at all. It just shows going fron N to dN with no explanation. I tried using the jacobian matrix to calculate the derivative but I'm not sure if this is the right approach. Most of the examples don't have a matrix from so i Know i'm doing something wrong.

The problem is a set from for reference. I need dN to move on to find the second fundamental forms and so forth

2. Nov 17, 2013

### metzky

Actually could i bring out the 1/sq u^2... out of the jacobian matrix then use the matrix to find the vector or no? so only the -v,-u,1 would be getting partially derived in the matrix?