Parametric curve question (determining unknown point)

In summary, the "Parametric curve question" involves finding an unknown point on a given parametric curve defined by specific equations. To determine this point, one typically uses the parametric equations to express the coordinates in terms of a parameter, then applies conditions or constraints to solve for the unknown parameter value, subsequently substituting it back to find the coordinates of the unknown point.
  • #1
cherry
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Homework Statement
A curve given parametrically by (x, y, z) = (3 - t, -1 - 3t^2, 2t + 2t^3). There is a unique point P on the curve with the property that the tangent line at P passes through the point (2, 8, 12). What are the coordinates of point P?
Relevant Equations
(x, y, z) = (3 - t, -1 - 3t^2, 2t + 2t^3)
My work so far:
IMG_5937C097F81C-1.jpeg


I am stuck because when I inputted the two possible values of t and k, neither solution worked. Where did I go wrong? Pointers would be appreciated! :)
 
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  • #2
cherry said:
Homework Statement: A curve given parametrically by (x, y, z) = (3 - t, -1 - 3t^2, 2t + 2t^3). There is a unique point P on the curve with the property that the tangent line at P passes through the point (2, 8, 12). What are the coordinates of point P?
Relevant Equations: (x, y, z) = (3 - t, -1 - 3t^2, 2t + 2t^3)

My work so far:
View attachment 338514

I am stuck because when I inputted the two possible values of t and k, neither solution worked. Where did I go wrong? Pointers would be appreciated! :)
I see where I went wrong and it turns out t = -1 and k = 2 is the correct solution.
Where would I go from there to determine point P?
 
  • #3
cherry said:
I see where I went wrong and it turns out t = -1 and k = 2 is the correct solution.
Hello @cherry, and
:welcome: ##\qquad## !​

Kudos for finding out!
1705184825929.png
is indeed 12, not 16. (*)

cherry said:
Where would I go from there to determine point P?
You have ##(x, y, z) = (3 - t\; , -1 - 3t^2\; , 2t + 2t^3) \ !##(*) quoting is a lot easier if ##\LaTeX## is used. See link to guide at lower left of edit window...

[edit] I didn't check if k=2 is the correct solution, nor whether the other solution is invalid
[edit] did now.

##\ ##
 

FAQ: Parametric curve question (determining unknown point)

What is a parametric curve?

A parametric curve is a type of curve in mathematics where the coordinates of the points on the curve are expressed as functions of a parameter. This parameter is often denoted by 't'. For example, in a 2D plane, a parametric curve can be represented as x(t) and y(t), where x and y are functions of t.

How do you determine an unknown point on a parametric curve?

To determine an unknown point on a parametric curve, you need to know the parameter value 't' corresponding to that point. Once you have the value of 't', you can substitute it into the parametric equations x(t) and y(t) (or z(t) in 3D) to find the coordinates of the point.

What information is needed to find an unknown point on a parametric curve?

To find an unknown point on a parametric curve, you need the parametric equations that define the curve and the specific parameter value 't' for which you want to find the point. Sometimes, additional conditions or constraints may be given to determine the appropriate value of 't'.

Can you determine an unknown point if only partial information is given?

Determining an unknown point with partial information can be challenging. If you have partial information, such as one coordinate of the point or a relationship between coordinates, you may be able to solve for the parameter 't' and then use it to find the other coordinates. However, without sufficient information, it may not be possible to uniquely determine the point.

What are some common applications of parametric curves?

Parametric curves are used in various fields, including computer graphics, physics, engineering, and robotics. They are useful for modeling motion, designing curves and surfaces, and solving problems involving paths and trajectories. They also appear in the study of differential equations and in the representation of complex shapes and patterns.

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