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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Equation of plane through a point and perpendicular to planes

I'm asked to find an equation of the plane $(π)$ through the point $P(2,1,-1)$ which is perpendicular to the planes $(π_1):2x+y-3=0,(π_2):x+2y+z=2$ My try was: $\mathbf n_1 \times \mathbf n_2=(1,-2,3)$ is parallel to $(π)$ and $(π)$ is perpendicular…
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A question about a dotted spiral

A dotted spiral has the origin as its center. Its first point is one unit from the origin. Its second point has a distance of the square root of two from the origin and one unit from the first point. Its third point has a distance of the square root…
Robert
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Curvature of an elastic blade

I have a practical problem related to the design of a monochromator for a neutron beam. This device basically consists of an elastic metallic plate carrying the diffracting crystals, which is curved mechanically to achieve proper focusing…
jmichel
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Analytic Geometry question I can't solve

An isosceles triangle $ABC$ has 2 given vertices, $A(3,2)$ and $C (7,14$). The slope of AB is $\dfrac{1}{2}$. What are the coordinates of B? I could figure out that line AB = $\dfrac{1}{2}x + \dfrac{1}{2} $ I found that the length of AC = is…
JohnPhteven
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Prove that $x^3+y^3+z^3-3xyz=1$ defines a surface of revolution

Prove that the equation $x^3+y^3+z^3-3xyz=1$ defines a surface of revolution and find the analytical equation of its axis of revolution. I think that I need to apply Euler's formula, so that I get rid of the third-grade polynomial there:…
user171110
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line through $P(l,3)$ intersect ellipse at $A$ and $D$ and axis at $B$ and $D$. then min. of $|l|$

A line through $P(l,3)$ meets the ellipse $\displaystyle \frac{x^2}{16}+\frac{y^2}{9}=1$ at $A$ and $D$ and meets the $x$ axis and $y$ axis at $B$ and $C$ so that $PA.PD =PB.PC.$ find minimum value of $|l|$ equation of line through $P(l,3)$ is…
DXT
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$ax^2+2hxy+by^2+2gx+2fy+c=0$

The equation $$ax^2+2hxy+by^2+2gx+2fy+c=0$$ represents a pair of parallel lines. Prove that the equation of the line mid way between the two parallel lines us $hx+by+f=0$ My Attempt: Let the lines be $lx+my+n_1=0$ and…
pi-π
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I Conjecture the line $BC$ always passes through a fixed point with $\frac{x^2}{a^2}+\frac{y^2}{b^2}=1$

before I ask this question: and mathlove give a nice answer How prove this $BC$ always passes through a fixed point with $\frac{x^2}{4}+y^2=1$ I continue consider this following problem. if the fix point $A(u,v)$ on the ellipse $\Gamma:$…
math110
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Why do lines with slope further away from 0 bunch together?

Here's an image taken from the article: Frequentism and Bayesianism IV: How to be a Bayesian in Python. Since I can't add images, here's the link: Image It depicts lines generated with slopes between 0 and 10 in steps of 0.1 What accounts for the…
sntx
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Equation of even multiple of straight line

$$ x \cos \alpha + y \sin \alpha -p = 0$$ represents a straight line in polar form (or even taken in any other form), $$ (x \cos \alpha + y \sin \alpha -p )^3 = 0$$ represents 3 straight lines repeated, but why does not, $ (n\in \mathbb Z) $ $$ ( x…
Narasimham
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Coordinate geometry perpendicularity problem

Below is my problem picture Line $a$ runs parallel to $x$-axis. Line $b$ runs parallel to $y$-axis. When the two lines meet, then they become perpendicular to each other. Now, slope of line $a$ is $$m_1=\tan 0 = 0$$ And slope of line $b$ is…
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Removal of the xy term

By transforming to parallel axes through a properly chosen point (h,k) I was asked to prove that the following equation can be reduced to one containing only terms of the 2nd degree: $$12x^2-10xy+2y^2+11x-5y+2=0$$. What I did was shifted the origin…
Ayan Shah
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Simple analytic geometry question I need help with

Give the equation of a circle with the center $ (a,0) $ which is tangent to the line $ y = x $ I now have $ (x-a)^2 + y^2 = r^2 $ but I don't know how to continue.. please help!
JohnPhteven
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Trouble with formulation of an analytic geometry question

I'm having trouble understanding a certain question, so I am asking for an explanation of it. The question is asked in a different language, so my translation will probably be mistake-ridden, I hope you guys can overlook the mistakes (and of course…
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Radius-4 circle skewered on one line and touching another

Find the equation of the circle with radius $4$ units, whose centre lies on the line $4x+13y=32$ and which touches the line $4x+3y+28=0$. My Approach: Radius $r=4$ units Let $P(h,k)$ be the centre of the circle. Then $4h+13k=32$. Please help me to…
pi-π
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