Questions tagged [analytic-geometry]

Questions on the use of algebraic techniques for proving geometric facts. Analytic Geometry is a branch of algebra that is used to model geometric objects - points, (straight) lines, and circles being the most basic of these. It is concerned with defining and representing geometrical shapes in a numerical way.

Analytic geometry, also called coordinate geometry, mathematical subject in which algebraic symbolism and methods are used to represent and solve problems in geometry.

The importance of analytic geometry is that it establishes a correspondence between geometric curves and algebraic equations. This correspondence makes it possible to reformulate problems in geometry as equivalent problems in algebra, and vice versa; the methods of either subject can then be used to solve problems in the other.

Analytic geometry was introduced by René Descartes in $1637$ and was of fundamental importance in the development of the calculus by Sir Isaac Newton and G. W. Leibniz in the late $17^{th}$ cent. More recently it has served as the basis for the modern development and exploitation of algebraic geometry.

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Why is there unique plane which passes through given point and is parallel to given line

I was trying to solve one question which is asking to find a plane which passes through given point and is parallel to given line. The given point is $M(2,-5,3)$ and the given line is given as an interesection of the planes $2x-y+3z-1=0 \text{ and }…
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Regarding an answer on angular bisectors in 2D coordinate geometry.

I am aware that the following expression represents the two angular bisectors for two straight lines. $$\frac{a_{1}x+b_{1}y-c_{1}}{\sqrt{a_{1}^{2}+b_{1}^{2}}}=\pm \frac{a_{2}x+b_{2}y-c_{2}}{\sqrt{a_{2}^{2}+b_{2}^{2}}}\qquad $$ I had the following…
idunno
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Given two lines find the equation of the half of the angles between them

We have given two lines $7x-y-11=0$ and $x+y-5=0$ We should find the equations of the lines that are dividing the angles between those two lines on half. I dont know how to approach this problem because I'm not very good in analytical geometry. I…
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Rotation and circle equation proof correction

I need to prove, that an equation of a circle doesn't change if there's a rotation. So, I start with $$x^2+y^2+Dx+Ey+F=0$$ and by replacing my values of $x$ and $y$ with $$x=x'\cos\theta-y'\sin\theta$$ and $$y=x'\sin\theta+y'\cos\theta$$ which I…
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Determining a point's coordinates on a circle

So I have a circle (I know its center's coordinates and radius) and a point on the circle (I know its coordinates) and I have to determine the coordinates of another point on the circle which is exactly at the distance L from the first point.
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What is the function that maps circumferal distance onto circular area

A unit circle with points A and B are initially located at (1,0). Point A remains at (1,0) while point B moves counter clockwise along the circumference of the unit circle until it reaches (-1,0). AB represents a stretchable blade that shaves off…
Robert
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Line always passes through a fixed point for some parameters

My question goes like this If 5a+4b+20c=t, then what is the value of t for which the line ax+by+c-1=0 always passes through a fixed point? I tried but couldn't solve it so I looked at the solution. The solution says that the equation has 2…
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Express the coordinates $(x_1,y_1)$ in terms of $(x_0,y_0)$ and $t$

Question: Let $(x_0,y_0)$ be a point of the curve $y^2=ax^2+bx+c$ and $t$ is the slope of the line passing through $(x_0,y_0)$ and intersecting this curve in the point $(x_1,y_1)$. Express the coordinates $(x_1,y_1)$ in terms of $(x_0,y_0)$ and…
weilam06
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Perpendicular form of the straight line equation in n-dimensional space

A similar question was discussed before but it was in a 2-dimensional space. Perpendicular form of the straight line equation. So how can the derivation in a 2D space be generalized to an n-dimensional space? In other words, how can we derive the…
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For pair of st. lines , length of line joining feet of perpendiculars from $(f,g)$ to them is$\sqrt {4.\frac {(h^2-ab)(f^2+g^2)}{(a-b)^2+4h^2}}$

Consider a pair of straight lines through the origin, $$ax^2+2hxy+by^2=0$$ This can be written as, $$y=m_{1,2}x$$ where $m_{1,2}=-\frac {a}{h±\sqrt {h^2-ab}}$. Now, suppose a point $(f,g)$ whence perpendiculars are drawn to both the lines . Then the…
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Hyperbolic paraboloid

help me out with the following question. Find the coordinates of the vertex and equation of the hyperbolic paraboloid $4x^2-y^2-z^2+2yz-8x-4y+8z-2=0$
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Intersection of a cone of light from point $p=(x,y,z)$ and $xy$-plane

I am working on a programming problem where I want to display a cone of light from a point $p=(x,y,z)$ lying in space to some direction. For example, if $p=(0,0,1)$, and the light is facing straight down with angle of 90 degrees, the intersection at…
ZzZzZz
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Find $a$ so that a line is tangent, secant or external from a sphere

I am given the following problem: Given the line $$r \{ R = (1,0,a) + \lambda [a \quad a \quad 0]$$ and the sphere $$S \{ 8x^2 + 8y^2 +8z^2 - 16x +24y -8z + 19 = 0$$ find, relating to values of $a$, when the line is external, tangent and secant to…
bru1987
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How to get a implicit equation of this ellipse

If I give you the curve $\gamma (t) = ( \cos (t), \cos(t+a))$, how can I obtain an implicit equation? or which change of basis can I do to get the canonical implicit form?
HFKy
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Application of the concept of 'Imaginary Circle'?

In most analytic geometric books the equation of a circle is defined as the special case of a conic $ax^2 + by^2 + 2hxy + 2gx + 2fy + c = 0$ when $ a = b \neq 0$ and $h = 0$. Almost all books do not include the condition that the radius should be a…
Anon
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