Finding the Tangent Line to a Parametric Curve

In summary, the problem is asking for the tangent equations to the curve x=3t^2+1 and y=2t^3+2, which intercepts the point (4,3). The author initially attempts to use the formula for the slope of a tangent line, but realizes it may not work for all values of t. They then clarify the problem and suggest using the parametric equations to find the coordinates of the point on the curve corresponding to a given value of t. The conversation ends with a suggestion to use the given point and the calculated slope to find the tangent equations.
  • #1
Hobold
83
1

Homework Statement



This is a very basic problem, though it did confuse me a little:

Find the tangent equations to the curve [tex]x=3t^2+1 \ , \ y = 2t^3+2[/tex] which intercepts the point (4,3).

Homework Equations



---

The Attempt at a Solution



I took [tex]\frac{dy}{dx} = t = \frac{y-y_0}{x-x_0} = \frac{y-3}{x-4} \rightarrow y=t(x-4)+3[/tex]

What to do next? I don't think the equation works for all t.
 
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  • #2
Hobold said:

Homework Statement



This is a very basic problem, though it did confuse me a little:

Find the tangent equations to the curve [tex]x=3t^2+1 \ , \ y = 2t^3+2[/tex] which intercepts the point (4,3).
Are you sure the above is right? If x = 4, then t = +/-1, but when t = 1, y = 4 and when t = -1, y = 0.
Hobold said:

Homework Equations



---

The Attempt at a Solution



I took [tex]\frac{dy}{dx} = t = \frac{y-y_0}{x-x_0} = \frac{y-3}{x-4} \rightarrow y=t(x-4)+3[/tex]

What to do next? I don't think the equation works for all t.
 
  • #3
Yes, I'm sure, those are the functions.

I believe the problem asks for a tangent of the graphic which will intercept the point (4,3) in R^2, which is not necessarily in the graphic of the function.
 
  • #4
OK, I misunderstood.

So let's say we're talking about the point on the curve whose coordinates are (x0, y0), that correspond to t = t0.

Can you use the parametric equations to write x0 and y0 in terms of t0. Then use the point (4, 3) and calculate the slope of the line segment between (x0, y0) and (4, 3), which you know is equal to t0.
 

Related to Finding the Tangent Line to a Parametric Curve

1. What is a tangent line to a curve?

A tangent line to a curve is a straight line that touches the curve at one point, but does not intersect with the curve at any other point. It represents the slope of the curve at that specific point.

2. Why is the tangent line important?

The tangent line is important because it helps us understand the behavior of the curve at a particular point. It can also be used to approximate the curve and calculate its slope or rate of change at that point.

3. How do you find the equation of a tangent line to a curve?

The equation of the tangent line can be found using the derivative of the curve at the specific point. The slope of the tangent line is equal to the derivative of the curve at that point. Then, using the point-slope formula, the equation of the tangent line can be written in the form y = mx + b, where m is the slope and b is the y-intercept.

4. Can a curve have more than one tangent line at a point?

No, a curve can only have one tangent line at a point. This is because the tangent line represents the slope of the curve at that point, and the slope of a curve can only have one value at a specific point.

5. What is the difference between a tangent line and a secant line?

A tangent line touches the curve at one point, while a secant line intersects the curve at two points. The secant line can be thought of as an approximation of the curve between those two points, while the tangent line represents the exact slope of the curve at a single point.

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