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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How to find one endpoint with the other end point and a point 1/3 away from it

If you had one endpoint and a point 1/3 of the way away from that endpoint. How would you find the other endpoint?
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Semi vertical angle of Right circular cone

Show that the semi vertical angle of the right circular cone $$4(x^2+y^2)-9z^2=0$$ is $$\arctan\left(\frac{3}{2}\right)$$ I took a cone whose vertex is at zero and axis is z axis , then I found the equation of cone and compared it with the given…
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How to represent $x = -6$ in terms of $y$?

I have the equation $x = 0$ which needs to only be graphed when the y values are between 0 and 3. This can be represented as the following equation. $$x=0y,\quad \{0
Riz-waan
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Show that the product of perpendiculars drawn from the two points

Show that the product of the perpendiculars drawn from the two points $(\pm \sqrt {a^2-b^2} , 0)$ upon the line $\dfrac {x}{a} \cos \theta + \dfrac {y}{b} \sin \theta = 1$ is $b^2$. My Attempt: Let $p_1$ and $p_2$ be the lengths of perpendiculars.…
pi-π
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Find the equations of two straight lines each of which is parallel to

Find the equations of two straight lines each of which is parallel to and at a distance of $\sqrt {5}$ from the line $x+2y-7=0$. My Attempt: The equation of any line parallel to $x+2y-7=0$ is $x+2y+k=0$ The distance between these two lines…
pi-π
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A straight line l intersects the hyperbola $\frac {x^2}{a^2} -\frac { y^2}{b^2} = c$ at points P1 and P2.

(i) Suppose M is the midpoint of P1 and P2, find the coordinates of M. (ii) If the coordinates of M is (h,k), find the equation of l. There are all unknown in this question. Should we let the equation l be $y=mx+c$ ? Or there are other way to solve?
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Intersection point and plane of 2 lines in canonical form

I have a math task which says: find the intersection point and the plane for these lines: p: (x-2) / 1 = (y-1) / (-1) = (z-3) / 1 and q: x / 1 = (y-1) / 1 = (z-1)/ 1 I dont know how to find the int point in this form, I know I…
ellie
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Locus of the intersection of two tangent lines at a point on a function and its inverse

Find the Cartesian equation of the locus of the point $P$ which is the intersection of the tangent lines at a point $t$ on the graphs of $y=e^x$ and $y=\ln(x)$ My attempt Equation of tangent at point $(t,e^t)$ on $y=e^x$ $y=e^tx+e^t(1-t)$ Equation…
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How to find the orthocentre of a triangle whose coordinates and area are given

I have a triangle in $ xy $ plane, whose vertices being $$ A(k, –3k)$$ $$ B(5, k) $$ $$ C(–k, 2) $$ Where $k$ is an integer. And area is $28$ sq. units. How to find the coordinates of its orthocentre? What I've done By using area formula, I got…
Fghj
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In what ratio is the line joining the points $(1,3)$ and $(2,7)$ divided by the line $3x+y=9$?

In what ratio the line, joining the points $(1,3)$ and $(2,7)$, divided by the line $3x+y=9$? My Attempt: Let the ratio be $m:n$. Then $$(x,y)=\left(\frac {mx_2+nx_1}{m+n} , \frac {my_2+ny_1}{m+n}\right)$$ $$=\left(\frac {m.2+n.1}{m+n}, \frac…
pi-π
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Determine the equation of the line the portion of which, intercepted by the axes, is divided by the point $(-5,4)$ in the ratio of $1:2$.

Determine the equation of the line the portion of which, intercepted by the axes, is divided by the point $(-5,4)$ in the ratio of $1:2$. My Attempt: Let the equation of straight line be $$ax+by+c=0$$ It passes through the point…
pi-π
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Reduction of the Linear Equation to Normal Form

The equations $$Ax+By+C=0$$ and $$x\cos \alpha + y\sin \alpha - p=0$$ will represent one and the same straight line if their corresponding coefficients are proportional: $$\dfrac {\cos \alpha}{A} = \dfrac {\sin \alpha}{B}=\dfrac {-p}{C}=k(\textrm…
pi-π
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Prove that every first degree equation in $x$ and $y$ always represents a straight line.

Prove that every first degree equation in $x$ and $y$ always represents a straight line. My Attempt: Let the first degree equation in $x$ and $y$ be $$ax+by+c=0$$. Let $A(x_1, y_1)$, $B(x_2, y_2)$ and $C(x_3,y_3)$ be any three points in the locus…
pi-π
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Classification Of $3x^2+4xy-6y^2-z=0$

Classify the quadratic surface $3x^2+4xy-6y^2-z=0$ Looking at $$\begin{vmatrix}\lambda-3 & -2 & 0\\-2 & \lambda+6 & 0\\ 0 & 0 & 0\end{vmatrix}=0$$ So how can I classify it?
newhere
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$y = \theta x_1 + (1 − \theta)x_2$

I am following Prof. Boyd’s lecture on Convex optimization. In the second lecture it is mentioned that the eq. $y = \theta x_1 + (1 − \theta)x_2$ represents the points lying on a line joining $x_1$ and $x_2$. I am unable to find a proof for…