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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What is a coordinate system?

What's a coordinate system? I was watching a Khan video about coordinates with respect to orthonormal bases. It is mentioned that orthonormal bases make for "good coordinate systems". I didn't ...
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0answers
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Ellipsoidal Coordinates Geometrically

Is there a quick, geometric, way of writing down (the square root of?) the Cartesian coordinates $$\begin{align} x^2 &= (a^2+\xi)(a^2+\eta)(a^2+\zeta)/(b^2-a^2)(c^2-a^2)\\ y^2 &= ...
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2answers
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converting kph and heading to xyz velocity vector

I am writing software (in C++) that is required to send out messages from our simulation system to another simulation system. Problem is we track the simulation object's current speed (kph) and ...
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1answer
20 views

How to find the $ x,y$ coordinates of a point in between $2$ points in $3$ dimension

Point $1 = (0,0,0)$ Point $2 = (5,6,7)$ Given that point $3$ have a $z$-coordinate of $3$, how can I find the $x,y$ coordinates of point $3$?
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1answer
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How many different ways are there to go from $(0,0,0)$ to $(3,3,3)$?

There is a cube that is on the $(x, y, z)$ coordinates. How do I construct a systematic way to go from $(0,0,0)$ to $(3,3,3)$? Which subject should I study for this question? Please help me! I'm ...
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1answer
36 views

Equation of tangent on Cartesian plane given center and radius of a circle

If I have a generic circle with radius $r$ and center $(h, k)$, and a tangent line with point of tangency $(x, y)$, can you give me the equation of the tangent line? Thanks!
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1answer
66 views

Point transformation of ODEs

I am trying to understand a passage in the introduction to this book, which deals with algorithmical procedures to analytically solve ODEs. Specifically, I do not understand how the ODE $$ y''(y+x) + ...
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1answer
32 views

maximum radius of a circle inscribed in an ellipse

Consider an ellipse with major and minor axes of length 10 and 8 resp. The radius of the largest circle that can be inscribed in this ellipse, given that the centre of this circle is one of the focus ...
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1answer
39 views

N points in a circle around a point on a sphere.

Consider a 3D sphere: $(x_{c}, y_{c}, z_{c})$ : cartesian coordinates of the center $r$ : the radius Consider a random point on the surface of this sphere of coordinates : $(x_{0}, y_{0}, ...
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Separation of the centre of mass coordinates for an N-electron atom

Can anyone tell me how to derive [A8.5] and [A8.6] in Appendice 8 of "Bransden: Physics of solid state matter", in this screenshot: http://i.imgur.com/zSCkVnI.jpg ? It should be easy, but damn me I ...
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What does the phrase “uncoupled across coordinate directions” mean in this text?

The following paragraph is from a paper about comparison of maneuvering target tracking models.In the paragraph it talks about constant acceleration models. The above models are simple but crude. ...
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create local coordinate system with one axis aligned with a line

I have a line from p1=(x1,y1,z1) to p2=(x2,y2,z2) in global coordinate system. I am trying to create a local coordinate system with origin at p1, whose local z axis i.e. z' is aligned with (parallel ...
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23 views

Integration over length

Trying to integrate over length with natural coordinates I stumbled upon the following equation. Where can I find the explanation of it? Thanks. $$ \int_H L_1^\alpha L_2^\beta \,dH = ...
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0answers
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New Axis calculation

I have a task whereby I use an accelerometer to calculate acceleration for a vehicle. The problem I am attempting to solve is to allow the accelerometer to be in any oriertaion. Basically I have a ...
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0answers
28 views

Differential Operators in different coordinates

How does one show this identity? $$\frac{\partial^2}{\partial x^2}+\frac{\partial^2}{\partial y^2}=\frac{\partial^2}{\partial r^2}+{1\over r}\frac{\partial}{\partial r}+{1\over ...
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3answers
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Alternative form of equation of circle?

In a problem set I was solving, one of the solutions used the equation of a circle in the form $$(x-h)^2 + (y-k)^2 + \lambda(ax + by +c) = 0$$ where, $(h,k)$ is any point on the circle $ax+by+c ...
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1answer
52 views

Find the maximum length of a line segment enclosed in a given area

$A = \{ (x, y) : x = u + v , y = v , (u^2) + (v^2) \le 1 \}$ . Then what is the maximum length of a line segment enclosed in this area? My friend suggested the answer $\sqrt{5}$, but I think it ...
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1answer
30 views

Change of Basis - Homework Question

Please help me understand what is being asked, I feel I am missing something. Compute the change of basis matrix for each of the bases, and use it to find the coordinate vector v with respect to B ...
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1answer
30 views

How to determine the direction of one point from another, given their coordinates?

If I have the coordinates of two points, how would I determine what direction the second point lies in, relative to the first point? Specifically, I'm writing an application that involves basically ...
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2answers
24 views

Region closer to one given point than to any other given point

(Q) *Consider 6 points located at P0=(0,0), P1=(0,4), P2=(4,0), P3=(-2,-2), P4=(3,3), P5=(5,5). Let R be the region consisting of all points in the plane whose distance from P0 is smaller than that ...
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1answer
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Problem of a circle tangent to three other circles

Two circles with centres A and B and radii 14 and 7 units respectively touch each other externally. M is the mid point of segment DE and is the centre of the circle with radius 21 units. The two ...
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1answer
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Finding conditions for a point residing in the interior of an ellipse

I have an ellipse with the equation $x^2+2y^2-2xy-1=0$. Suppose $(h,k)$ is a point residing in the interior region of the ellipse. Should this point satisfy any condition in terms of $h,k$?
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homogenous coordinate system vs cartesian coordinate

“The homogeneous coordinate system is used in projective geometry as much of the math ends up simpler in homogeneous coordinate space than it does in a regular Cartesian space.” Excerpt From: Haemel, ...
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3D cartesian cordinates to 3D isometric cordinates

I am working on Isomer opensource project https://github.com/jdan/isomer and I need to convert 3D cartesian cordinates to 3D isometric cordinates. We already have 3D iso to 2D cartesian ...
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1answer
31 views

Straight Lines and Curves

If the line $y=x\sqrt3$, intersects the curve $x^3+y^3+3xy+5x^2+3y^2+4x+5y-1=0$, in three points $A,B,C$. If $O$ is the origin, then what's the product $OA\cdot OB\cdot OC$?
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1answer
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Rotation of axes help?

This is not a duplicate of my other question in regard to this. I really am not understanding this rotation of axes stuff. If we want to graph a 45 degree shifted ellipse for example, we can think of ...
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1answer
22 views

Y-Coordinate of a Point - Notation

Given point $P$ on curve $\omega$, what expression is generally use to denote the $y$-coordinate of point $P$, also, the $x$-coordinate. Would it be $P_y$? Also, let $\omega$ be in $\mathbb{R}^2$, not ...
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1answer
43 views

Find a point using multilateration or triangulation

Suppose we have 3 points in a 3d coordinate system with the following locations. A=(100,0,0) B=(0,100,100) C=(0,0,100) If there is a 4th point D, where the distances from A, B, and C are known, can ...
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1answer
191 views

Finding the expected value of the length of a minimal spanning tree of n randomly generated nodes bound in a box with edge length a.

Say we specify a number (n) of random points (x,y), bound within the axes and x=a, y=a. Given the number of points and the constraints on the boundaries, how can you calculate the expected value of ...
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1answer
33 views

Finding the locus of a mid-point

Let $A$ be the fixed point $(0, 4)$ and $B$ be a moving point $(2t, 0)$. Let $M$ be the mid-point of $AB$ and let the perpendicular bisector of $AB$ meet the $y$-axis at $R$. Find the locus of the ...
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2answers
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Calculating the expected value of n randomly generated numbers?

Say I have a random number generator that will generate x numbers - not necessarily integers - on the continuous range between a and b. How can I calculate the expected values for these numbers? My ...
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2answers
30 views

Rotation of axes give the same point in space?

I am playing around with rotation of axes formulas and not getting it. I don't understand how this rotates anything when it is just giving you different coordinates for the SAME point in space. How ...
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1answer
39 views

Cartesian Line to Projective Coordinates

I have an equation of a line written in slope intercept form $y = mx + b$ How would I translate it from the 2d space into the projective space? I have been reading ...
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2answers
62 views

How to find center of a circle given 2 points on the circle and the radius?

I would like to find an equation that I can put into excel to calculate the coordinates for the center of the circle. Given P1 (a) 33855.05, (b) 21129.55 P2 (c) 33745.04, (d) 21221.69 Radius 590 I ...
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1answer
44 views

Geometric interpretation of a complex solution

A straight line in 2-D $x+y=3$ and a circle in 2-D $x^2+y^2=4$ do not have a point of intersection in the plane containing the two. But on solving these equations analytically, on gets 2 complex ...
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2answers
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Is the reference point (x, y) above or below the non-linear equation?

BACKGROUND In short, I have a series of 3 to 10 data points that will be used to represent a curve. For example: $X=0, Y=10$ $X=4, Y=7$ $X=9, Y=12$ $X=16, Y=10$ What I am trying to do is ...
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1answer
132 views

Help understanding polar coordinates and conversion between polar and rectangular

I'm not understand this. I understand that you can take normal functions with x's and y's and convert them into polar coordinates. I also understand that the polar form of that function will have the ...
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1answer
73 views

How to find the equation of a line which intersects these lines at 90 degrees?

How to find the equation of a line which intersects these lines at 90 degrees? $p\equiv \dfrac{x}{2}=\dfrac{y+1}{0}=\dfrac{z-2}{1}$ $q\equiv \dfrac{x-1}{1}=\dfrac{y-2}{1}=\dfrac{z+5}{0}$ Since the ...
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1answer
20 views

Find a vector in cartesian coordinates given its relative location to another vector in spherical coordinates

Here is my problem: -I have an arbitrary normalized vector N in cartesian coordinates -I am trying to find normalized vector M, also in cartesian coordinates -I am given the azimuth and polar ...
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1answer
17 views

Rotation operator for a point in a coordinate system linearly derived from Cartesian coordinates

For some experimental and practical reason, I have created a new coordinate system in the form $$x^\prime_i=T_{ij}x_j$$ where $T_{ij}$ isn't a square matrix. $x_i$ is standard Cartesian coordinates, ...
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1answer
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An error in Wikipedia? (trigonometry)

https://en.wikipedia.org/wiki/N-sphere In "Spherical coordinates" section the hyperspherical coordinates are results of arccosinus function. In some other sources there is arccotangent instead: ...
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1answer
38 views

Find coordinates for points on circle given R, 2 Points, and angle or 2 points and center?

I would like to find coordinates for points on a circle given: Radius of circle Coordinates of 2 points on the circle Angle of point 1, center, and point 2. Ultimately, I would like to write a ...
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0answers
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Parabolic Coordinates Radius

Given Cartesian $(x,y,z)$, Spherical $(r,\theta,\phi)$ and parabolic $(\varepsilon , \eta , \phi )$, where $$\varepsilon = r + z = r(1 + \cos(\theta)) \\\eta = r - z = r(1 - \cos( \theta ) ) \\ \phi ...
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Fit cartesian coordinate system to point cloud

I have a cloud of points that initially lie in a plane and have a coordinate system attached to them. I then displace the points slightly, and I want to find how a 'best fit' of the coordinate system ...
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1answer
31 views

Angle between planes , when only two points are given [closed]

Find the equation of plane passing through points $[1,0,0]$ and $[0,1,0]$, and making an angle of $45°$ degree with the plane $x + y - 3 = 0$.
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Tangent definition

As far as the definition of a tangent goes it is a line that touches a curve only at one point. Now let us consider the sine function .At (pi)/2 it attains its maximum value and so does it at ...
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1answer
51 views

rotation matrix to axis angle

from wikipedia the above rotation matrix has a rotation of -74 degrees. What does it mean "around the axis (−1⁄3,2⁄3,2⁄3)"? How can I determine how many degrees is rotated on X axis, Y axis and Z ...
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1answer
51 views

“Rigorous” definition of Cartesian coordinates

I, like most, first learned about Cartesian coordinates very early on in my educational career, and so the most instructional way to think about them was that you place down some perpendicular lines ...
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1answer
38 views

Convex Sets and extreme supports

Let the set $S$ in $R^n$ consists of the origin $0$ and $n$ lineary independent vectors $T_1, \ldots, T_n$. Show that $C(S)$, the convex hull of of $S$, is the intersection of its extreme supports, ...
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41 views

Geometric reasoning and triangular coordinates

The following is from a book: I do not understand the sentence "... the point $(t_1, t_2, t_3)$ can be plotted by plotting $(t_1 = t_3, t_2 = t_3)$...", what is meant by the point $(t_1 = t_3, t_2 = ...