# Find if a Vecotr field is perpendicular to a curve

1. Dec 20, 2008

### swraman

1. The problem statement, all variables and given/known data

http://math.berkeley.edu/~teleman/53f08/review2.pdf [Broken]
Question #4

2. Relevant equations

Not sure

3. The attempt at a solution

I have no idea...
I really dont care about the answer, I have that, but I just dont know how to find out if a vector field is perpendicular to a curve.
Thanks

Last edited by a moderator: May 3, 2017
2. Dec 20, 2008

### HallsofIvy

Staff Emeritus
Do you mean perpendicular at every point on the curve? You determine whether a single vector is perpendicular to a curve at a given point by taking the dot product of the vector with the tangent vector to the curve at that point. Can you generalize that to a vector field?

3. Dec 20, 2008

### neo86

If you want to find out if a vector field is perpendicular you have to check that the scalar product of the tangent vector of the curve and the Vector Field vanishes at every point of the curve.

Since you have given the curve only implicitly you would probably need implicit function theorem to actually get the tangent vector.

4. Dec 20, 2008

### Dick

The easy way to get a tangent direction is to take the cross product of the normals of the surfaces defined by the two equations.