Unit vector perpendicular to the level curve at point

In summary, to find the unit vector perpendicular to the level curve of f(x,y) = x^2y-10xy-9y^2 at (2,-1), we need to evaluate the gradient of the function at (2,-1) and normalize it. A level curve is a curve where the function takes a fixed value, and in this case, the level curves of f=x^2+y^2 are circles.
  • #1
Bestphysics112
24
2

Homework Statement


Find the unit vector perpendicular to the level curve of f(x,y) = x2y-10xy-9y2 at (2,-1)

Homework Equations


Gradient

The Attempt at a Solution


I'm not sure what it's asking. Wouldn't this just be the gradient of f(x,y) evaluated at (2,-1) then normalized? or am I missing something?
 
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  • #2
Bestphysics112 said:
Wouldn't this just be the gradient of f(x,y) evaluated at (2,-1) then normalized?
Yes. Is that a problem?
 
  • #3
Orodruin said:
Yes. Is that a problem?
No problem at all. I just wasn't sure what a level curve was.
 
  • #4
A level curve of a function is the curve such that the function takes a fixed value. For example, the level curves of f=x^2+y^2 are circles.
 
  • #5
Orodruin said:
A level curve of a function is the curve such that the function takes a fixed value. For example, the level curves of f=x^2+y^2 are circles.
Oh that makes much more sense. Thank you.
 

1. What is a unit vector perpendicular to a level curve at a specific point?

A unit vector perpendicular to a level curve at a specific point is a vector that is perpendicular to the tangent line at that point on the curve. It has a magnitude of 1 and is used to indicate the direction of the steepest ascent or descent of the function at that point.

2. How is a unit vector perpendicular to a level curve calculated?

To calculate a unit vector perpendicular to a level curve at a specific point, you first need to find the gradient vector of the function at that point. Then, you can use the cross product of the gradient vector and a vector in the direction of the tangent line to find the perpendicular vector. Finally, divide the resulting vector by its magnitude to get a unit vector.

3. Why is a unit vector perpendicular to a level curve important?

A unit vector perpendicular to a level curve is important because it helps us understand the direction of change of a function at a specific point. It can also be used to find the direction of the steepest ascent or descent of the function, which is useful in optimization problems.

4. Can a unit vector perpendicular to a level curve change at different points on the curve?

Yes, the unit vector perpendicular to a level curve can change at different points on the curve. This is because the gradient vector, which is used to calculate the perpendicular vector, can change direction and magnitude at different points on the curve.

5. How is a unit vector perpendicular to a level curve used in real-world applications?

A unit vector perpendicular to a level curve has many real-world applications, such as in physics, engineering, and economics. It can be used to find the direction of maximum change in a physical system, the direction of maximum efficiency in an engineering design, or the direction of maximum profit in an economic model.

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