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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Show that the locus of the centroids of equilateral triangles inscribed in the parabola $y^2=4ax$ is the parabola $9y^2-4ax+32a^2=0.$

Show that the locus of the centroids of equilateral triangles inscribed in the parabola $y^2=4ax$ is the parabola $9y^2-4ax+32a^2=0.$ I tried to solve it.I took three coordinates of the equilateral triangle as $(x_1,y_1),(x_2,y_2),(x_3,y_3)$ let the…
Brahmagupta
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How do I mathematically halve Orange Juice with my brother!

I need to calculate the height of a glass(frustum) where the volume is half of total volume. Obviously, at h/2, volume will not be v/2. So my question is, at what height from the bottom of the glass is volume equal to half of full volume. Where am I…
Phani
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If $P=(x_0,y_0)$ is a point in a focal chord of the parabola $x^2=4py$ then find the coordinates of the other point

$\textbf{Exercise:}$ If $\overline{PQ}$ is a focal chord of the parabola $x^2=4py$ and the coordinates of $P$ are $(x_0,y_0)$, show that the coordinates of $Q$ are $$ \left(\frac{-4p^2}{x_0},\frac{p^2}{y_0}\right) $$ (original…
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General Form of the equation of a straight line.

We all know the general form of the equation of a straight line which is $A x + B y + C = 0$ but my question is, what $A$ represent and what $B$ represent and what $C$ represent. Sorry I am not good in mathematics so I need your help. Clear…
Mo Haidar
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How to find vertex of a parabola from its second degree equation

Given a parabola with second degree equation as $$Ax^2 + Bxy + Cy^2 + Dx + Ey + F = 0 $$ assume that this isn't degenerate case, and $B^2-4AC=0$ How can I find its vertex position?
it4rb
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Equation of a circle given one point and two lines

Find the equation of the circle that pass through $(2,3)$ and are tangent to both the lines $3x - 4y = -1$ and $4x + 3y = 7$.
Rigoo
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points possible on a circle

Let $A, B, C, D$ and $E$ be five points marked in clockwise order, on the unit circle in the plane (with centre at origin). Let $\alpha$ and $\beta$ be real numbers and set $f(p)=\alpha x+\beta y$ where $P$ is a point whose coordinates are $(x,y)$.…
tattwamasi amrutam
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Show that the focus of the parabola lies on the nine point circle of the triangle.(dificult)

A parabola is drawn such that each vertex of a given triangle is the pole of the opposite side;show that the focus of the parabola lies on the nine point circle of the triangle and that the orthocentre of the triangle formed by joining the middle…
maths lover
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Why is this an ellipse?

On a textbook, I've arrived at the following function: $\displaystyle \phi(z)=\log{\frac{|z-\sqrt{(z²-1})|}{2}}$ and it says that the formula has a simple interpretation: the level curves of $\phi(z)$ are the ellipses with foci $-1, 1$. I know the…
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Find the equation of the plane that passes through the line of intersection of the planes...

Find the equation of the plane that passes through the line of intersection of the planes $4x - 2y + z - 3 = 0$ and $2x - y + 3z + 1 = 0$, and that is perpendicular to the plane $3x + y - z + 7 = 0$. This is what I got: $3x + 4y - z + 15 = 0$. Can…
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Recomputing arc center

Please excuse my poorly drawn doodle here, I'm almost inept at drawing. I'm attempting to compute i2, j2, x2, y2. Knowns: x1, y1, xk, yk, i1, j1, the arc is circular Constraints: resulting arc is circular cartesian co-ordinate…
Stephen
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What is the formula for the change of slope after a rotation of the coordinate system?

I have recently realized that the slope of a line depends on the coordinate system. Suppose we take the standard coordinate system and rotate it $45$ degrees (or, equivalently, $\pi / 4$ radians) counterclockwise. Then, lines of slope $1$ become…
user107952
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Is the result of the actions $\left((\vec A+\vec B) \times (\vec A\times \vec B)\right)\cdot(\vec A \times \vec B)$ depends by $\vec A$ and $\vec B$

I want to show that this action not depend by A and B vectors, I know that cross product of the same vector by itself is $0$. $$\left((\vec A+\vec B) \times (\vec A\times \vec B)\right)\cdot(\vec A \times \vec B)$$ I can use here in Associative…
Ofir Attia
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Find the projection of the point on the plane

I want to find the projection of the point $M(10,-12,12)$ on the plane $2x-3y+4z-17=0$. The normal of the plane is $N(2,-3,4)$. Do I need to use Gram–Schmidt process? If yes, is this the right formula? $$\frac{N\cdot M}{|N\cdot N|} \cdot N$$ What…
Ofir Attia
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Can you calculate the difference in two angles based on the difference in slope?

Say you have a curve y = f(x). I am looking at a tangent line at point A (line A) and a tangent line at point B (line B). Now let’s also define angle A as the angle between line A and, say, the x axis, and likewise angle B as the angle between line…
nenli
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