For questions about parametric equations, their application, equivalence to other equation types and definition.

learn more… | top users | synonyms

2
votes
0answers
25 views

Famous parametric curves that are solutions to differential equations

I know that the cycloid satisfies the differential equation $ \left( \frac{dy}{dx} \right)^2 - \frac{2r}{y} + 1 = 0. $ Are there other famous plane curves that are also solutions to a differential ...
0
votes
0answers
14 views

Parameterization of a closed curve on a sphere

I'm looking for a parameterization of a closed curve C on a sphere. assume the projections of C on y-z, x-z, x-y plane are f(x), g(y), h(z), respectively, and ${\oint}f(x)dx={\oint}g(y)dy=0$, and ...
0
votes
1answer
11 views

Determine if a parametric equation's trajectory lies on a circle?

I have a question as follows: Determine whether the following trajectory lies on a circle. If so, find the radius of the circle and show that the position vector and velocity vector are everywhere ...
0
votes
0answers
18 views

Make equation on nonparametric form

I have the following Points $(-1,-2,-6)$ and $(-1,-2,-12)$ if I write the line on parametric form I get $$x = -1 + (0*t)\\ y = -2 + (0*t)\\ z = -6 + 6t $$ I know how to solve it if I have more ...
0
votes
0answers
22 views

Find a complete sufficient statistic

Here is my problem : Suppose theta is a nonrandom parameter satisfying theta > 1. Suppose further that, given theta, Y1 , Y2, ... , Yn are i.i.d. observations with each density f_\theta(y) = (\theta - ...
-3
votes
1answer
43 views

Parameterizations of Lines.

Which of the following equations give alternate parameterizations of the line L parameterized by: r(t)=(1+2t)i +(2+2t)j -(1+4t)k? a. -(1+t)i-t*j+(3+2t)k b, (3-2t)i+(2-2t)j+(3-4t)k c. ...
7
votes
0answers
110 views

Length of parametric curve $\phi(t)=(f(t)\cos(t),f(t)\sin(t))$

Define the curve $\phi$ by $\phi(t):=(f(t)\cos(t),f(t)\sin(t))$, where $f$ be a strictly increasing infinitly many differentiable function . Find an explicit formula for the length of $\phi$ ...
0
votes
0answers
10 views

Parametric equation ( Planes)

The three planes α, β and γ have the equations: α: x-2y+z=3 β:2x+y-3z=1 γ: x+y+az=1 where a is a real number 1) Given that α intersect the xy-plane (with equation z=0) in a straight line. Find a ...
0
votes
1answer
37 views

Parameterizing an ellipse

Given the ellipse $(x-1)^2 + \frac{y^2}{4}= 1$, parametrize the curve in polar coordinates. I've forgotten something very basic here. Can someone help get me started?
2
votes
2answers
32 views

Where does the line x = 2 − t, y = 3t, z = −1 + 2t intersect the plane 2y + 3z = 6?

form this 2y + 3z = 6 equation i take the x = 0. therefor 2 - t = 0 and ...
0
votes
0answers
26 views

An example of a space curve with given normal and osculating planes

I am student currently taking calculus 3 and I recently was given a quiz with a very difficult question. The question relates to the chapters in my book which talk about "Arc Length and Curvature" and ...
0
votes
1answer
23 views

Horizontal and vertical tangents to a parametric curve

I'm not sure what my procedure should be when solving this problem: find all points with a horizontal tangent find all points with a vertical tangent find all inflection points $$x(t) = ...
0
votes
2answers
20 views

Paramertized ellipses

I have $a^2 = (4x-8)^2 + 4y^2$ and $b^2=(4x+8)^2 + 4y^2$ which I switch between every $t=\frac{n\pi}2$ How do I draw this touching the origin, and moving outwards, noting that ...
1
vote
5answers
62 views

Evaluating a contour integral where C is a square

I've been working problems all day so maybe I'm just confusing myself but in oder to do this, I have to the take the integral along each contour $C_1-C_4$ My issue is how to convert to parametric ...
0
votes
1answer
30 views

How can I get a smooth distortion on a circle with a function g(x,y)

Let's say, $$f(x,y)=x^2+y^2=1$$ gives the unit circle. Now I would like to get a smooth distortion on the circle with a function $g(x,y)$. my guess is to consider the perimeter as one dimension, so ...
12
votes
1answer
215 views

Connected unbounded sets $S\subset \Bbb{R}^n$ such that $x\mapsto ||x||^t$ is uniformly continuous on $S$?

Spending the night perusing my old answers, and this question left me wondering about the following. Let's equip $\Bbb{R}^n$ with the usual Euclidean metric, and let us consider the map ...
0
votes
1answer
44 views

How to parametrize a curve using polar coordinates

How do I parametrize a curve $(x^2+y^2)^2=40^2(x^2-y^2)$ using polar coordinates? then what period is $\theta$ in?
0
votes
1answer
19 views

Equation for simple parametric curve

My math skills are rusty. I want to find the parametric equation for the 5 vertices curve below. It consists of an ellipse with a rotating axes. I get stuck after this: $$x = a \cos(t) \cos(\theta) - ...
0
votes
0answers
13 views

How to design own the parametric vector?

I try to design the parametric vector that looks like a roller coaster I know that my equation will like $r(t) = A\sin(t)i + Btj+ C\cos(t)k$, but i want ...
0
votes
1answer
15 views

curve with vanishing tangent vector assumption

I am just reviewing some assumptions in Parametric representations The book says we assume 3-d curve has non-vanishing tangent vector. Why do we need to assume this Simply if we take $R^3$ then ...
1
vote
0answers
26 views

Parameterize the equation

Find a way of parameterizing the following curve: $y^2=\sin x $. I have already tried $x(t) = (\sqrt t, \sin^{-1} t) $ but this only gives part of the curve because of the nature of the sqrt function ...
0
votes
2answers
23 views

Show that if $v_1$ and $v_2$ are any two vectors in this plane, then for any two scalars, $c_1v_1 + c_2v_2$ is also a vector in the plane

Let $a,\,b$ and $c$ be constants (not all zero) and consider the equation $ax + by + cz = 0$, which has a graph that is a plane that passes through the origin in $\mathbb{R}^3$. Show that if $v_1$ and ...
0
votes
1answer
23 views

Is this parametric equation correct?

Am I able to just put the planes point into the equation and leave it at that? or am I wrong here? My parametric equation: (x,y,z) = (3,-2,1)+ t(2,1,-3) + s(1,-2,4)
-1
votes
0answers
17 views

Evaluate the line integral with Euler.

Need some help evaluating this line Intergral. $\int$$_c$ xy${e^y}$$^z$ dy Where C: x = 4t ; y = 3t$^2$ ; z = 3t$^3$ ; 0$\le$t$\le$1 Any help would be great. Thanks.
0
votes
2answers
34 views

Parametric / vector question.

Question 10 [10 points] Let L be the line with parametric equations $$ x = −6−3t $$ $$ y = 6+3t $$ $$ z = −8+2t $$ Find the vector equation for a line that passes through the point P=(−1, 2, 3) and ...
0
votes
2answers
26 views

How to define distance between two functions in a non-linear space (example of non-linear space: shape space)?

Suppose I have two parametric circle $f_1=(acost,asint)$ and $f_2=(bcos t,bsint)$, $t\in(0,2\pi),a>0,b>0$, which lies in some non-linear space. Are there any way, how to define the ...
1
vote
2answers
25 views

Creating a parametric Equation when given the points of a collinear line?

$(-70, 3)$, $(88, 81)$, and $(246, 159)$ are three collinear points. Write parametric equations for $x$ and $y$. (In other words, write equations that produce points when $t$-values are assigned.) ...
1
vote
1answer
47 views

Parametrizing shapes, curves, lines in $\mathbb{C}$ plane

I've been struggling with parametrizing things in the complex plane. For example, the circle $|z-1| = 1$ can be parametrized as $z = 1 + e^{i\theta}$. I'm not sure how this was done. I understand how ...
0
votes
1answer
25 views

Orthogonal parameterization

Consider the function $$f(a,b,c,d):=\frac{\left(a^*\right)^2b^2-\left(b^*\right)^2a^2+\left(c^*\right)^2d^2-\left(d^*\right)^2c^2}{a^*a+c^*c}$$ With complex parameters $a,b,c$ and $d$ Now find any ...
1
vote
1answer
41 views

Ray-sphere intersection: t-value of the intersection points

You have a sphere centered at [1,2,3] with radius 3, and a ray from [10,10,10] in the direction [-1,-1,-1]. Write the implicit equation for the sphere, the parametric equation for the ray, and compute ...
1
vote
1answer
8 views

How do I successfully combine these two paramaterized equations?

I'm working on a set of equations that would tell a hypothetical robot soccer player whether or not to pass a ball to a teammate. After a lot of algebra, I arrived at these equations for the partial ...
3
votes
1answer
23 views

Parametrization of the implicit curve $F(x,y)=a_1\cos x+a_2\sin x+a_3\cos y+a_4\sin y-b=0$

I am trying to find a parametrization for the curve defined implicitly by $$ F(x,y)=a_1\cos x+a_2\sin x+a_3\cos y+a_4\sin y-b=0, $$ where $a_1$, $a_2$, $a_3$, $a_4$ and $b$ are constants satisfying ...
1
vote
2answers
53 views

How to show that the curve $ (x,y,z) = \langle \cos t, \sin t, c\sin t\rangle $ is an ellipse?

Show that the curve $$(x,y,z) = \langle \cos t, \sin t, c\sin t\rangle $$ is an ellipse in the plane it lies on. $$x^2 + y^2 = (\sin t)^2 + (\cos t)^2 = 1$$ $$x^2 + (z/c)^2 = (\sin t)^2 + (\cos ...
0
votes
4answers
47 views

Using parametric differentiation for $\frac{\operatorname d \! y}{\operatorname d \!x}$?

Hi so I'm in my calculus class and the teacher gave us a problem to do. I'm not quite sure how to attack this question. He's given us a couple of steps but I don't understand. If someone can further ...
1
vote
1answer
25 views

Determine whether the points (5, -6, 10) and (3, 3, 8) are on the line x = 2 + t, y = 3 - 3t, z = 4 + 2t

I've gone about trying to solve this by assuming the x co-ordinate lies on the line, and then determining whether the other points lie on that line according to that ie. If x = 5, then 5 = 2 + t, ...
0
votes
2answers
40 views

Parametric form of square

What is the appropriate parametric equation of the boundary of a square? For example, the unit circle has a parametric equation $x(t)=\cos(t)$ and $y(t)=\sin(t)$.
1
vote
1answer
35 views

Parametrization of a Complex Path/Contour Integration

How would I parametrize the path which is a straight line from 1 to a complex point z? Does $\delta (t) = z^t$ make any sense?
0
votes
0answers
75 views

Converting this 3D plane parametric equation to non-parametric

I had these 3 planes to put into parametric equation: (5, 4, −8),(1, 6, −3) and (7, −2, 5) so I put it into this parametric equation: (x,y,z) = (5,4,-8) + t(-4,2,5) + s(2,-6,13) But i am having ...
4
votes
4answers
29 views

If $x=t^2\sin3t$ and $y=t^2\cos3t$, find $\frac{dy}{dx}$ in terms of $t$

If $x=t^2\sin3t$ and $y=t^2\cos3t$, find $\frac{dy}{dx}$ in terms of $t$. This is how I tried solving it: $$ \frac{dx}{dt} = 2t\sin3t + 3t^2\cos3t \\ \frac{dy}{dt} = 2t\cos3t - 3t^2\sin3t \\ ...
1
vote
1answer
26 views

Parameterizing $y = 2 -\sin \frac{\pi x}{2}$

I am trying to parametrize the part of the curve $$ y = 2 -\sin \frac{\pi x}{2} $$ from (0, 2) to (1, 1). I tried the difficult paramaterization $x=t$ and obtained $$ y=2-\sin \frac{\pi t}{2} $$ ...
0
votes
1answer
19 views

Finding the initial direction of a parametric curve?

With the parameters: $$x(t)=1-\sin^2t$$ $$y(t)=2+\cos^2t$$ It starts at (1,3) and when t=pi/2 it's at (0,2), so I'm tempted to say it's going down to the right; is this correct? In general, is there ...
3
votes
2answers
42 views

Number of Curvature Maxima of a 2D Cubic Bezier curve

I am trying to prove that a standard cubic Bezier curve can only have at most 2 curvature maxima over $t \in [0,1]$. Assuming that no 3 adjacent control points are colinear, the curvature will either ...
2
votes
0answers
40 views

Launch angle required to hit coordinate (x,y) with air resistance

Finding Angle of Elevation to hit X, Y and Wikipedia Angle required to hit coordinate work, but don't calculate air resistance. Is there a way to find the launch angle of a projectile required to hit ...
1
vote
1answer
23 views

why can't we eliminate the parameter of straight lines in higher dimensions

Why we can't remove the parameter and find the Cartesian equation of straight lines in higher dimensions ?
0
votes
0answers
39 views

Parametric Equation of a parabola from the derivative of the parametric equation of a circle

Find the velocity and trajectory to throw a ball from a Ferris Wheel to a friend standing below. The Ferris Wheel has a diameter of 16 meters and its highest point is 19 meters above the ground. It ...
0
votes
0answers
54 views

Find point on rotated curve

I have a curve $f(t)$ that has been rotated through an angle $\theta$, and also have defined a given offset $Y$ from the curve origin. Using the equation $Y=x*sin(\theta)+y*cos(\theta)$ which ...
0
votes
1answer
26 views

From one parametric form of a curve to another one

I've the following parametric equations for a curve: $$\begin{cases}x(t)=a(t-\tanh(t))\\y(t)=a \operatorname{sech(t)}\end{cases}$$ Is there a way to switch from these equations to the equations: ...
0
votes
1answer
43 views

Simplify a parametric equation with hyperbolic trigonometric functions

I've the following parametric equations for a curve: $$\begin{cases}x(t)=a\cdot \operatorname{sech} (t) \\ y(t)=a\cdot(t-\tanh(t))\end{cases}$$ Now let $\theta(t)=-\arctan(\sinh(t))$ how does the ...
0
votes
1answer
25 views

Parametric equations for the tractrix

The cartesian equation of the tractrix is:$$y=\pm\left(a\cdot \operatorname{arcsech}^{-1}\left(\frac{x}{a}\right)-\sqrt{a^2-x^2}\right)$$ where $a>0$ is a real parameter and $x$ varies from $0$ to ...
1
vote
1answer
53 views

Jacobian of parametrized ellipsoid with respect to parametrized sphere

I'm not even sure how best to phrase this question, but here goes. Given $\theta$ (elevation) and $\phi$ (azimuth), the unit sphere can be parametrized as $ x = \cos(\theta)\sin(\phi) \\ y = ...