Parametric Equations Tanget lines

In summary, Parametric equations are used to describe curves or surfaces in terms of parameters, while tangent lines are lines that touch a curve or surface at only one point and have the same slope as the curve or surface at that point. These two concepts are related in that parametric equations can help determine the slope of a curve at a specific point, which is necessary to find the equation of a tangent line. Parametric equations can also be used to find the equation of a tangent line by first determining the slope at a specific point and then using the point-slope form of a line. However, there may be limitations to using these techniques, as other methods may be more efficient or accurate in certain situations.
  • #1
600burger
64
0
I am asked to find the equation of the tanget line to the curve at the givien points. (y -y1 = m(x1-x))

The point is:
(-2/sqrt(3), 3/2)

Parametric Equations are:
where t = theta

x = 2*cot(t)
y = 2*sin^2(t)

How would i find what theta is in this set, inorder to solve dy/dx numericlly to get my slope (m)?
 
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  • #2
For what value of theta does x = -2/sqrt(3) and y = 3/2?

cookiemonster
 
  • #3


To find the value of theta for the given point, we can plug in the x and y coordinates into the parametric equations. This will give us two equations:

-2/sqrt(3) = 2*cot(t)
3/2 = 2*sin^2(t)

We can then solve for t by rearranging the first equation to get cot(t) = -1/sqrt(3), and using the identity cot(t) = cos(t)/sin(t), we can substitute in -1/sqrt(3) for cot(t) in the second equation. This will give us:

3/2 = 2*(1-cos^2(t))

Simplifying, we get:

3/2 = 2-2cos^2(t)

Rearranging and dividing by 2, we get:

cos^2(t) = 1/4

Taking the square root, we get:

cos(t) = ±1/2

From this, we can determine two possible values for theta: t = π/3 and t = 2π/3. We can plug these values back into the original parametric equations to verify that they do indeed give us the given point (-2/sqrt(3), 3/2).

Now that we have determined the value of theta, we can use it to find the slope of the tangent line at that point. We can do this by taking the derivative of both parametric equations with respect to t and then plugging in the value of theta. This will give us:

dx/dt = -2*csc^2(t)
dy/dt = 4*sin(t)*cos(t)

Substituting in t = π/3 or t = 2π/3, we get:

dx/dt = -2*4/3 = -8/3
dy/dt = 4*√3/2 = 2√3

Finally, we can use the formula for the slope of a tangent line, m = dy/dx, to find the slope at the given point:

m = (dy/dt)/(dx/dt) = (2√3)/(-8/3) = -√3/4

Now that we have the slope, we can use the point-slope form of a line to write the equation of the tangent line:

y - (3/2) = (-√3/4)(
 

What are parametric equations and tangent lines?

Parametric equations are a set of equations used to describe a curve or surface in terms of one or more independent variables, known as parameters. Tangent lines, on the other hand, are lines that touch a curve or surface at only one point and have the same slope as the curve or surface at that point.

How are parametric equations and tangent lines related?

Parametric equations are often used to determine the slope of a curve or surface at a specific point, which is necessary to find the equation of a tangent line. The parameters in the parametric equations represent the coordinates of the point where the tangent line touches the curve or surface.

How do you find the slope of a curve using parametric equations?

To find the slope of a curve at a specific point, you can use the parametric equations to determine the values of the parameters at that point. Then, you can use the derivative of the parametric equations to find the slope at that point.

Can parametric equations be used to find the equation of a tangent line?

Yes, parametric equations can be used to find the equation of a tangent line. Once you have determined the slope of the curve at a specific point, you can use the point-slope form of a line to find the equation of the tangent line.

Are there any limitations to using parametric equations and tangent lines?

While parametric equations and tangent lines can be useful in many situations, they may not always be the most efficient or accurate method for finding equations of curves or surfaces. In some cases, other mathematical techniques may be more appropriate.

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