# What is Parametric equations: Definition and 208 Discussions

In mathematics, a parametric equation defines a group of quantities as functions of one or more independent variables called parameters. Parametric equations are commonly used to express the coordinates of the points that make up a geometric object such as a curve or surface, in which case the equations are collectively called a parametric representation or parameterization (alternatively spelled as parametrisation) of the object.For example, the equations

x

=
cos

t

y

=
sin

t

{\displaystyle {\begin{aligned}x&=\cos t\\y&=\sin t\end{aligned}}}
form a parametric representation of the unit circle, where t is the parameter: A point (x, y) is on the unit circle if and only if there is a value of t such that these two equations generate that point. Sometimes the parametric equations for the individual scalar output variables are combined into a single parametric equation in vectors:

(
x
,
y
)
=
(
cos

t
,
sin

t
)
.

{\displaystyle (x,y)=(\cos t,\sin t).}
Parametric representations are generally nonunique (see the "Examples in two dimensions" section below), so the same quantities may be expressed by a number of different parameterizations.In addition to curves and surfaces, parametric equations can describe manifolds and algebraic varieties of higher dimension, with the number of parameters being equal to the dimension of the manifold or variety, and the number of equations being equal to the dimension of the space in which the manifold or variety is considered (for curves the dimension is one and one parameter is used, for surfaces dimension two and two parameters, etc.).
Parametric equations are commonly used in kinematics, where the trajectory of an object is represented by equations depending on time as the parameter. Because of this application, a single parameter is often labeled t; however, parameters can represent other physical quantities (such as geometric variables) or can be selected arbitrarily for convenience. Parameterizations are non-unique; more than one set of parametric equations can specify the same curve.

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1. ### Solve this problem that involves parametric equations

My take; Part (a); ##\dfrac{dy}{dx}=\dfrac{1}{t}## therefore, ##y-2at=\dfrac{1}{t}(x-at^2)## ##ty-2at^2=x-at^2## ##ty=x+at^2## implying that ##T## has co-ordinates ##(-at^2,0)##. ##SP=\sqrt{(a-at^2)^2+(0-2at)^2}## ##SP=\sqrt{4a^2t^2-2a^2t^2+a^2t^4+a^2}## ##SP=\sqrt{a^2t^4+2a^2t^2+a^2}##...
2. ### Solve the given problem involving parametric equations

My take; ##y=\dfrac{c^2}{x}## ##y+x\dfrac{dy}{dx}=0## ##\dfrac{dy}{dx}=\dfrac{-y}{x}## ##y-\dfrac{c}{t}=-\dfrac{y}{x}(x-ct)## ##yt-c=-\dfrac{yt}{x}(x-ct)## ##xyt-cx=-yt(x-ct)## ##c^2t-cx=-cx+yct^2## ##c^2t-cx=-cx+ytct## ##c^2t-cx=-cx+c^2t## ##⇒-cx=-cx## ##⇒cx=cx## Therefore it...
3. ### Prove that PA=2BP in the problem involving parametric equations

My take; ##\dfrac{dy}{dx}=\dfrac{-1}{t^2}⋅\dfrac{1}{2t}=\dfrac{-1}{2t^3}## The equation of the tangent line AB is given by; ##y-\dfrac{1}{t}=\dfrac{-1}{2t^3}(x-t^2)## ##ty=\dfrac{-1}{2t^2}(x-t^2)+1## At point A, ##(x,y)=(3t^2,0)## At point B, ##(x,y)=(0,1.5t)##...
4. ### Find the Cartesian equation given the parametric equations

hmmmmm nice one...boggled me a bit; was trying to figure out which trig identity and then alas it clicked :wink: My take; ##x=(\cos t)^3 ## and ##y=(\sin t)^3## ##\sqrt[3] x=\cos t## and ##\sqrt[3] y=\sin t## we know that ##\cos^2 t + \sin^2t=1## therefore we shall have...
5. ### Correct Parametrization for Calculating Area of a Tube?

Hi, I'm trying to find the area of this tube using ##\int \int ||\vec{N}|| ds d\theta##. However, I get 0 as result which is wrong. So at this point, I'm wondering if I made a mistake during the parametrization of the tube. This is how I parametrized the tube. ##S(s, \theta) = (cos(s), sin(s)...
6. ### MHB Parametric Eqs: Find Line & Plane, Find Triangle Area

Let P (1, 2, 3), Q (2, 3, 1), and R (3, 1, 2). (a) Derive the parametric equations for the line that passes through P and Q without resorting to the known formula. (b) Derive the equation of the plane that passes through the points P, Q, and R without resorting to the known formula. (c) Find the...
7. ### How Does the Point of Tangency Move in Circular Motion?

Solution: The point of tangency of the string moves around the circle at ##2\pi## radians per second. First, we compute the position of the point of tangency of the string with the bobbin. Because this is simply a revolution around a circle of radius 10, the parameterization of the point of...

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10. ### MHB 243 parametric equations and motion direction

11.1 Parametric equations and a parameter interval for the motion of a particle in the xy-plane given. Identify the paritcals path by finding a Cartestian equation for it $x=2\cos t, \quad 2 \sin t, \quad \pi\le t \le 2\pi$ (a) Identify the particles path by finding a Cartesian Equation the...
11. ### Find the scalar, vector, and parametric equations of a plane

Homework Statement Find the scalar, vector, and parametric equations of a plane that has a normal vector n=(3,-4,6) and passes through point P(9,2,-5) Homework EquationsThe Attempt at a Solution Finding the scalar equation: Ax+By+Cz+D=0 3x-4y+6z+D=0 3(9)-4(2)+6(-5)+D=0 -11+D=0 D=11...
12. ### B How do you create a + and π sign using multivariable (x,y,z)

I am taking a high school multivariable calculus class and we have an end-of-semester project where we trace out some letters etc., except that they all have to be connected, continuous and differentiable everywhere. My group's chosen to do Euler's formula, but so far we are having problems...
13. ### Writing vector and parametric equations for a line that....

Homework Statement [/B] Write vector and parametric equations for the line that goes through the points P(–3, 5, 2) and Q(2, 7, 1). Homework EquationsThe Attempt at a Solution First I find the direction vector for PQ. PQ=Q-P = (2,7,1)-(-3,5,2) =[2-(-3),7-5,1-2] =5,2,-1 PQ= (5,2,-1) Now I...
14. ### I Eliminating the Parameter from Helix Equation

Let's say you have a helix defined parametrically as r(t) =<sin(t), cos(t), t> Is it possible to eliminate t and write an equation for this helix just in terms of x, y, and z?
15. ### B Parametric Equations- Ball travel

Suppose a baseball is hit 3 feet above the ground, and that it leaves the bat at a speed of 100 miles an hour at an angle of 20° from the horizontal. I've got the parametric equations in terms of x and in terms of y, and I have values plotted and a graph sketched. My question is in regards to...

50. ### Parametric equations for the portion of the parabola y=x^2?

Homework Statement Find the parametric equations for the portion of the parabola y=x^2 from (-1,1) to (3,9) Homework Equations None that I know of. The Attempt at a Solution Using knowledge of parametric equations I am not sure how to start. My teacher never went over this...