Finding parametric equations of a tangent line

In summary, To find the parametric equations of the tangent line at the point (-2,2,4) to the curve of intersection of the surface z=2x2-y2 and the plane z=4, you can take the gradient of both surfaces and use the cross product of the two to find a vector perpendicular to both normals. This vector can then be used to find the parametric equations of the tangent line.
  • #1
grog
23
0

Homework Statement



Find parametric equations of the tangent line at the point (-2,2,4) to the curve of intersection of the surface z=2x2-y2 and the plane z=4

Homework Equations



Not sure


The Attempt at a Solution



Not sure quite how to approach this. take the gradient of 2x^2-y^2 and just plug for x=rcos[tex]\Theta[/tex] and y=r sin[tex]\Theta[/tex] ?

That seems too simple..
 
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  • #2
The gradient gives you a normal direction for each surface. Then the tangent is perpendicular to both normals. How can you find a vector perpendicular to two other vectors?
 
  • #3
so I would end up with 4x-2y and zero for the two normal vectors? and then take the cross product of the two? I think I may be confusing some concepts here.
 
  • #4
grog said:
so I would end up with 4x-2y and zero for the two normal vectors? and then take the cross product of the two? I think I may be confusing some concepts here.

Probably. The gradient is a vector. Those don't look like vectors. Better check the definition of 'gradient'.
 

Related to Finding parametric equations of a tangent line

1. What are parametric equations of a tangent line?

Parametric equations of a tangent line are equations that describe the coordinates of a point on a curve at a specific position, usually in terms of a parameter, such as time or distance.

2. How do you find the parametric equations of a tangent line?

To find the parametric equations of a tangent line, you first need to find the derivative of the curve at the given point. Then, use this derivative to find the slope of the tangent line. Finally, use the point-slope form of a line to write the parametric equations.

3. Why are parametric equations of tangent lines useful?

Parametric equations of tangent lines are useful because they allow us to represent a curve in a more simplified way. They also help us to find the coordinates of points on the curve at specific positions, which is important in many applications, such as physics and engineering.

4. Can you find parametric equations of a tangent line for any curve?

Yes, it is possible to find parametric equations of a tangent line for any curve as long as the curve is differentiable at the given point. If the curve is not differentiable, the tangent line does not exist.

5. Is it possible to have more than one tangent line at a given point?

Yes, it is possible to have more than one tangent line at a given point. This can happen if the curve has a sharp point or cusp at that point. In this case, each tangent line would have a different slope and therefore different parametric equations.

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