Questions on coordinate systems, a geometric method where a point in n-dimensions is assigned a corresponding n-tuple of numbers.

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2
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1answer
74 views

Using the Dirac delta function to find the density of point masses/charges

Here is an example from a textbook: Suppose there is a unit charge or unit mass at the point $(x,y,z)=(-1,\sqrt{3},-2)$; then in rectangular coordinates, the ...
0
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1answer
23 views

Get two specific coordinates on a linear function.

I've been trying to build an algorithm for my Unity3D project to get some specific coordinates, but I got stuck with some math problem. I have two coordinates of ...
2
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2answers
61 views

Angle of rotation based on direction cosines

I have a question which is bothering me for days! Suppose that we have a fixed frame $XYZ$ and a moving frame $xyz$ in 3D. The moving frame is orthonormal and is defined based on the fixed one using 9 ...
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0answers
20 views

Relative Motion between two rotating frames

I am looking for mathematical relations between equations of motion between two rotating frames. Relating the said motion by first going to a globally fixed frame is not an issue but how to approach ...
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0answers
11 views

The existence of a specific kind of coordinate system

Suppose a massive, perfectly spherical ball is fixed on a point in space, and that there is a second free particle of negligible mass. I have noticed that the magnitude of the force exerted on this ...
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2answers
26 views

Solving vector equations of planes

Find the line of intersection of two planes denoted by: $r=\overrightarrow{b}+\lambda(\overrightarrow{b}-\overrightarrow{a})+\nu(\overrightarrow{a}+\overrightarrow{c})$ $r=\overrightarrow{c}+\alpha(\...
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2answers
24 views

Determine whether two segments P1Q1 and P2Q2 have a common point if the (x,y) coordinates of their end points is known?

Does this question have a solution? I think it's impossible to know if line segments P1Q1 and P2Q2 intersect at all with just the information about their end points Q1 and Q2. Thanks.
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0answers
14 views

Cylindrical Coordinate System

I am to write equations of each side for a cylinder.The problem is stated below: There is a cylinder...One cuts it from somewhere near the center point ( height wise ) . So the cylinder is now split ...
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1answer
91 views

How can you find the distance between the center and edges of a rectangle - a line from centre to a edge at an angle $\theta$?

I have a case where I know the coordinates $(x,y)$ of the center of the rectangle and its edges where the line is dropped anywhere on the edges $a(x_1,y_1),b(x_2,y_1),c(x_1,y_2),d(x_2,y_2)$. Say I ...
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0answers
18 views

Cartesian coordinates conventions

Is there any historical account of how did the Cartesian coordinate system get its current conventions of orientation and representation? Are there any mathematical reasons for these conventions?
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0answers
63 views

Vector Laplacian operator in orthogonal curvilinear coordinates

I'm looking for a simple expression for the vector Laplacian $\nabla^2\mathbf{A}$ in orthogonal curvilinear coordinates. Actually, I don't require the whole thing, just the part of $\mathbf{u}_i\...
1
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1answer
31 views

Matrix to represent transformation $T(a_0+a_1t+a_2t^2) = a_1+2a_{2}t$ with respect to a certain basis

I'm having so much trouble understanding this very concept.. This is a problem from the book. The Mapping $T:P_2\to P_2$ is defined by $T(a_0+a_1t+a_2t^2)=a_1+2a_2t$ is a linear transformation. ...
3
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0answers
21 views

Single atlas implies global normal coordinates?

Let $M$ be a class $C^k$-Riemannian manifold and suppose there exists an atlas $\langle U,\psi\rangle$ for $M$ containing only one global chart. Does this imply that the Riemmanian $Log_p\,(:=Exp_p^{...
2
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1answer
69 views

Integral Calculus: Plane Areas in Rectangular Coordinates

Find the area bounded by the given curves: $y^2+2x-2y-3=0$ and the $y$-axis (using horizontal & vertical strip)
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2answers
25 views

Linear Algebra Coordinate Systems Isomorphism

This is an excerpt from the book. Let $B$ be the standard basis of the space $P_3$ of polynomials; that is let $B=\{1,t,t^2,t^3\}$. A typical element $p$ of $P_3$ has the form $p(t) = a_0 + a_1t+ ...
0
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1answer
19 views

formula to locate x and y coordinates from two point with x and y known and distance to third point known as well

updated pictureI am trying to find the formula or at least the name of this operation to locate x and y coordinates for a point from two other reference points with x and y known and distance to third ...
2
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1answer
99 views

Pullback metric, coordinate vector fields..

I'm doing this computation on $\mathbb{R}^3$ with cylindrical coordinates $(r, \theta, z)$, (which aren't defined on the whole of $\mathbb{R}^3$, but I don't care about that) and I seem to get a ...
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0answers
15 views

Limiting points

For a system of coaxial circles why are there only 2 limiting points? Shouldn't there be infinite limiting points? After all system of coaxial circles are pairs of circles which have same radical axis,...
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0answers
29 views

Direction angle of Line segment in polar coordinates

I have a line segment given by two points $A$ and $B$, that are $(r_1,\theta_1)$ and $(r_2,\theta_2)$ in Polar coordinates. I know that the direction angle of the line segment is given by: $$\...
1
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1answer
77 views

Coordinate transformations and interpreting what the Jacobian determinant describes

Apologies for a perhaps rather trivial question, but I really want to get the concept cleared up in my head. I understand that when one changes from one coordinate system there is an appropriate ...
0
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1answer
55 views

Why aren't area of triangle not same when calculated by different methods in this case

I came across a question today. Two mutually perpendicular straight lines through the origin forms an isosceles triangle with the line $2x + y = 5$. Then the area of the triangle is ? I know ...
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0answers
26 views

Relationship between Normal coordinates and Spherical Coordinates

I am using the following coordinates on $S^3: (\psi, \theta, \phi)$ where $$\begin{cases}x_0 = \sin\psi,\\ x_1 = \sin\psi \cos\theta,\\ x_2 = \sin\psi \sin\theta \cos\phi,\\ x_3 = \sin\psi \sin\...
2
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4answers
111 views

Calculation of $\min$ distance between $x^2+y^2=9$ and $2x^2+10y^2+6xy=1$

Calculation of $\min$ distance between $x^2+y^2=9$ and $2x^2+10y^2+6xy=1$ $\bf{My\; Try::}$ Using the fact that the distance between two curve is independent of shifting. So put $x=u+v$ and $y=u-v$ ...
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2answers
33 views

Can anyone provide a good explanation to converting a vector in cartesian coordinates to cylindricals?

I am sorry about the perhaps trivial question, but for some reason I am really struggling to do this. I was recently taught about curvilinear coordinates, which I believe provides a system for ...
1
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2answers
25 views

Coordinates of a matrix

So on the textbook, it gives an example: If the basis of B matrix is{$\begin{bmatrix}1&0\\ 0&0\end{bmatrix}, \begin{bmatrix}0&1\\ 0&0\end{bmatrix},\begin{bmatrix}0&0\\ 1&1\...
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1answer
19 views

Trigonometry: Find points coordinates in equally arms triangle

h have a equally arms triangle. The angle on point C is not 90 degrees. I have: The coordinates of point $C(C_x, C_y)$ The coordinates of the end point of $h$, $H(H_x, H_y)$ The length of $C$ (...
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1answer
26 views

Curve connecting two points in $\mathbb{R}^n$ passing through a hyperplane

Let $\pi$ and $\lambda$ be two distinct permutations of $1, 2, . . . , n$, and consider the points $p := (\pi(1),\pi(2), ... , \pi(n))$ and $r:= (\lambda(1), \lambda(2), ... , \lambda(n))$ in $\mathbb{...
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2answers
54 views

Find the equation of tangent at origin to the curve $y^2=x^2(1+x+x^2)$

How do I find the equation of tangent at $(0,0)$ to the curve $y^2=x^2(1+x+x^2)$ ? Differentiating and putting the value of $x$ and $y$ gives an indeterminate form. Can we trace the curve and ...
2
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0answers
48 views

Calculate the Angle between two vectors in 3d Spherical Coordinates

I have two vectors in spherical coordinates, both originating at the origin and both with the same magnitude equal to one. One is vertical: {1,0,0} and the other undefined: {Ms,Mt,Mp}. The other one ...
4
votes
1answer
59 views

Why do we need the equation of pair of straight lines?

I was studying about the straight lines in coordinate geometry and came across this topic named 'pair of straight lines'. It started in my book directly with "If we multiply the equation of two lines ...
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0answers
14 views

Translate and Rotate mesh

I have a mesh constituted of some vertices in 3d space, let's call them $(x_1,y_1,z_1),(x_2,y_2,z_2),\cdots,(x_n,y_n,z_n)$. The mesh's central point is $(0,0,0)$. How to find out the new coordinates ...
2
votes
3answers
49 views

New coordinates after clockwise rotation of triangle?

The figure below represents a triangle $PQR$ with initial coordinates of the vertices as $P(1,3)$, $Q(4,5)$ and $R(5,3.5)$. The triangle is rotated in the $X-Y$ plane about the vertex $P$ by angle $\...
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0answers
23 views

Coordinates change movement problem

yesterday I asked a related question that was a specific case of my problem. It was solved here: Geometry/ Triangles problem but I would want to know if its possible to get a generic universal ...
0
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1answer
68 views

Trigonometric position function and intersection

I have the following position function for a point: $x(t) := C_x - (S_x-C_x) \cdot \cos(t\cdot\theta) + (S_y-C_y) \cdot \sin(t\cdot\theta) + t \cdot v_x$ $y(t) := C_y - (S_x-C_x) \cdot \sin(t\cdot\...
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0answers
20 views

How to perform statistical test for two sets of points?

(I have asked this question originally on Cross Validated; however, no good answer and someone suggested me to ask the question here). Thanks a lot in advance if anyone can help. We know that we can ...
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0answers
18 views

$A: \mathbb R^3 \to \mathbb R^3$ what is the representation of $A$ under coordinate change? (Tensor)

For our initial homework on Tensor Calculus we have to do the following: Consider a map $A: \mathbb R^3 \to \mathbb R^3$, where we use local coordinates $\mathbf{x}$ given by $x^1,x^2$ and $x^3$. ...
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0answers
49 views

How does one determine whether a coordinate basis is orthogonal or not?

Apologies for what is perhaps a very basic question, but I have been studying differential geometry with a view to gain a deeper understanding of general relativity and I have hit a stumbling block. ...
2
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0answers
33 views

How to determine changing scale factors when performing coordinate transfomations?

To explain: I have two coordinate systems. One $(x,y)$ and the other $(x',y')$ as seen in this diagram. Coordinate systems I am trying to convert the coordinate in the $(x,y)$ system to the rotated ...
1
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1answer
42 views

Get coordinates in a scaled and translated canvas

I'm drawing an image to a scaled and translated HTML5 canvas. It's zoomed to a certain point on the image to be more specific, so only a smaller partition is visible. In this smaller part, I want to ...
0
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4answers
34 views

Feynman lectures, Volume I, chapter 13-4

While reading Feynman lectures on Physics, volume I, Chapter 13-4, I found following assumption, which I don't understand: Then, since $r^2 = \rho^2 + a^2$, $\rho\,d\rho = r\,dr$. Therefore ... ...
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2answers
54 views

Finding the equation of a circle from the equation of its tangents

Given the equation of a pair of lines : $36x² - 63xy + 20y² + 54x - 17y - 10 =0.$ If the circle touches one of the lines at (-3,-1) and the other at some point then find the equation of the circle....
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0answers
23 views

Calculating the sun position fails

could you help me find the mistake(s) in my calculation of the sun position today on hawaii at 16:00? I'm following this Wikipedia article. Number of days since 2000/01/01 (2016/01/29): $$n =5873$...
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0answers
16 views

Relations between unit vectors in polar and curvilinear coordinates

I'm a bit confused about the relations between unit vectors in curvilinear and polar coordinates in a plane. Let $u_{R}$ be the radial unit vector in polar coordinates and $u_{N}$ the normal unit ...
2
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1answer
37 views

Rational points on a line

This question is quite unique. Does there exist some point in the coordinate system such that any line passing through it has at most 2 rational points lying on it?
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0answers
31 views

Trying to develop a formula for relative angle relationships in fixed space

Fixed space is defined relative to origin $(0,0,0)$. Fixed space has an origin with angles $(0,0,0)$ as well. A particle $P$ has $(x,y,z)$ coordinates relative to the origin: $P_x$, $P_y$, and $P_z$....
0
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1answer
21 views

Rectangular to polar conversion angle error

I am trying to determine the polar form of the following rectangular vector: -105 + 140j The polar form is $\sqrt(-105)^2+140^2$ = 175 and the angle is ...
0
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2answers
36 views

If $x=r\cos(\theta)$ then in $?=r\cos(\theta+a)$ what is $?$ equal to?

What I mean by $r\cos(\theta+a)$ is that it's the same function $r\cos(\theta)$ but it's translated by $a$ units, if this makes any sense. I just want to know what it means in terms of $x$.
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0answers
48 views

What does it mean for a polar coordinate system to have basis vectors?

So I understand that every element of a vector space can be represented uniquely by a linear combination of the basis vectors: $v=\alpha_1v_1+\cdots+\alpha_nv_n$ Then coordinates to those basis ...
1
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1answer
40 views

Change of Variables in Laplacian

I know how to prove $$\nabla^2(\frac{1}{r}) = -4\pi\delta^3(\textbf{r}),$$ where in Spherical coordinates, $$ \nabla^2 = {\frac{1}{r^2} \, \frac{\partial}{\partial r} \left( r^2 \, \frac{\partial}{\...
0
votes
1answer
31 views

Rotating a 3 coordinate point

Im having trouble figuring out how to rotate the z axis 90 degrees. For a programming im making example new_x = y; // For a 90 degree clockwise rotation, the new x is the original y, new_y = ...