Finding Eccentricity of A Hyperbola
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Given an asymptote to an hyperbola and that a line perpendicular to it, intersects it at a single point, we need to find its eccentricity.
Asymptote : $5x-4y+5=0$ and Tangent : $4x+5y-7=0$.
I thought that if we consider asymptote to be limiting tangent at infinity, then the point of intersection $(3/41,55/41)$ should lie on the director circle of the hyperbola as it is the locus of the perpendicular tangents. I am finding too many variables to handle here. And I suspect this question should be solved by an argument for a specific type of hyperbola (Maybe rectangular), but I could use a hint over here
conic-sections
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add a comment |
$begingroup$
Given an asymptote to an hyperbola and that a line perpendicular to it, intersects it at a single point, we need to find its eccentricity.
Asymptote : $5x-4y+5=0$ and Tangent : $4x+5y-7=0$.
I thought that if we consider asymptote to be limiting tangent at infinity, then the point of intersection $(3/41,55/41)$ should lie on the director circle of the hyperbola as it is the locus of the perpendicular tangents. I am finding too many variables to handle here. And I suspect this question should be solved by an argument for a specific type of hyperbola (Maybe rectangular), but I could use a hint over here
conic-sections
$endgroup$
$begingroup$
The orthoptic for an ellipse and a hyperbola is its director circle. Please google 'director circle' .
$endgroup$
– Sarthak Rout
Dec 7 '18 at 9:10
$begingroup$
Google “orthoptic” and “director circle” yourself. The orthoptic of an ellipse is its director circle, but the orthoptic of a hyperbola is neither of its director circles.
$endgroup$
– amd
Dec 7 '18 at 9:20
$begingroup$
Look, I googled and I got this Wiki: In geometry, the director circle of an ellipse or hyperbola is a circle consisting of all points where two perpendicular tangent lines to the ellipse or hyperbola cross each other. And Orthoptic of a hyperbola as per wiki" The orthoptic of a hyperbola x^2/a^2 − y^2/b^2 = 1, a > b, is the circle x^2 + y^2 = a^2 − b^2 (in case of a ≤ b there are no orthogonal tangents, see below)". And , that is the director circle of the hyperbola. Please elaborate.
$endgroup$
– Sarthak Rout
Dec 7 '18 at 9:29
$begingroup$
There appear to be conflicting articles and terminology (not the first time). In en.wikipedia.org/wiki/Orthoptic_(geometry) a hyperbola’s orthoptic is pointedly not called its director circle; en.wikipedia.org/wiki/Hyperbola also avoids calling the orthoptic the director circle, but also uses the term “circular directrix” for the latter. Unlike the orthoptic, these circles exist for all hyperbolas, a useful trait if you’re going to use them for construction. A footnote suggests that the term “director circle” is used differently in German and English.
$endgroup$
– amd
Dec 7 '18 at 10:10
1
$begingroup$
At any rate, without further information or assumptions, I think that the best you can do here is to state an upper bound for the eccentricity.
$endgroup$
– amd
Dec 7 '18 at 10:11
add a comment |
$begingroup$
Given an asymptote to an hyperbola and that a line perpendicular to it, intersects it at a single point, we need to find its eccentricity.
Asymptote : $5x-4y+5=0$ and Tangent : $4x+5y-7=0$.
I thought that if we consider asymptote to be limiting tangent at infinity, then the point of intersection $(3/41,55/41)$ should lie on the director circle of the hyperbola as it is the locus of the perpendicular tangents. I am finding too many variables to handle here. And I suspect this question should be solved by an argument for a specific type of hyperbola (Maybe rectangular), but I could use a hint over here
conic-sections
$endgroup$
Given an asymptote to an hyperbola and that a line perpendicular to it, intersects it at a single point, we need to find its eccentricity.
Asymptote : $5x-4y+5=0$ and Tangent : $4x+5y-7=0$.
I thought that if we consider asymptote to be limiting tangent at infinity, then the point of intersection $(3/41,55/41)$ should lie on the director circle of the hyperbola as it is the locus of the perpendicular tangents. I am finding too many variables to handle here. And I suspect this question should be solved by an argument for a specific type of hyperbola (Maybe rectangular), but I could use a hint over here
conic-sections
conic-sections
edited Dec 9 '18 at 15:51
Sarthak Rout
asked Dec 7 '18 at 8:14
Sarthak RoutSarthak Rout
488
488
$begingroup$
The orthoptic for an ellipse and a hyperbola is its director circle. Please google 'director circle' .
$endgroup$
– Sarthak Rout
Dec 7 '18 at 9:10
$begingroup$
Google “orthoptic” and “director circle” yourself. The orthoptic of an ellipse is its director circle, but the orthoptic of a hyperbola is neither of its director circles.
$endgroup$
– amd
Dec 7 '18 at 9:20
$begingroup$
Look, I googled and I got this Wiki: In geometry, the director circle of an ellipse or hyperbola is a circle consisting of all points where two perpendicular tangent lines to the ellipse or hyperbola cross each other. And Orthoptic of a hyperbola as per wiki" The orthoptic of a hyperbola x^2/a^2 − y^2/b^2 = 1, a > b, is the circle x^2 + y^2 = a^2 − b^2 (in case of a ≤ b there are no orthogonal tangents, see below)". And , that is the director circle of the hyperbola. Please elaborate.
$endgroup$
– Sarthak Rout
Dec 7 '18 at 9:29
$begingroup$
There appear to be conflicting articles and terminology (not the first time). In en.wikipedia.org/wiki/Orthoptic_(geometry) a hyperbola’s orthoptic is pointedly not called its director circle; en.wikipedia.org/wiki/Hyperbola also avoids calling the orthoptic the director circle, but also uses the term “circular directrix” for the latter. Unlike the orthoptic, these circles exist for all hyperbolas, a useful trait if you’re going to use them for construction. A footnote suggests that the term “director circle” is used differently in German and English.
$endgroup$
– amd
Dec 7 '18 at 10:10
1
$begingroup$
At any rate, without further information or assumptions, I think that the best you can do here is to state an upper bound for the eccentricity.
$endgroup$
– amd
Dec 7 '18 at 10:11
add a comment |
$begingroup$
The orthoptic for an ellipse and a hyperbola is its director circle. Please google 'director circle' .
$endgroup$
– Sarthak Rout
Dec 7 '18 at 9:10
$begingroup$
Google “orthoptic” and “director circle” yourself. The orthoptic of an ellipse is its director circle, but the orthoptic of a hyperbola is neither of its director circles.
$endgroup$
– amd
Dec 7 '18 at 9:20
$begingroup$
Look, I googled and I got this Wiki: In geometry, the director circle of an ellipse or hyperbola is a circle consisting of all points where two perpendicular tangent lines to the ellipse or hyperbola cross each other. And Orthoptic of a hyperbola as per wiki" The orthoptic of a hyperbola x^2/a^2 − y^2/b^2 = 1, a > b, is the circle x^2 + y^2 = a^2 − b^2 (in case of a ≤ b there are no orthogonal tangents, see below)". And , that is the director circle of the hyperbola. Please elaborate.
$endgroup$
– Sarthak Rout
Dec 7 '18 at 9:29
$begingroup$
There appear to be conflicting articles and terminology (not the first time). In en.wikipedia.org/wiki/Orthoptic_(geometry) a hyperbola’s orthoptic is pointedly not called its director circle; en.wikipedia.org/wiki/Hyperbola also avoids calling the orthoptic the director circle, but also uses the term “circular directrix” for the latter. Unlike the orthoptic, these circles exist for all hyperbolas, a useful trait if you’re going to use them for construction. A footnote suggests that the term “director circle” is used differently in German and English.
$endgroup$
– amd
Dec 7 '18 at 10:10
1
$begingroup$
At any rate, without further information or assumptions, I think that the best you can do here is to state an upper bound for the eccentricity.
$endgroup$
– amd
Dec 7 '18 at 10:11
$begingroup$
The orthoptic for an ellipse and a hyperbola is its director circle. Please google 'director circle' .
$endgroup$
– Sarthak Rout
Dec 7 '18 at 9:10
$begingroup$
The orthoptic for an ellipse and a hyperbola is its director circle. Please google 'director circle' .
$endgroup$
– Sarthak Rout
Dec 7 '18 at 9:10
$begingroup$
Google “orthoptic” and “director circle” yourself. The orthoptic of an ellipse is its director circle, but the orthoptic of a hyperbola is neither of its director circles.
$endgroup$
– amd
Dec 7 '18 at 9:20
$begingroup$
Google “orthoptic” and “director circle” yourself. The orthoptic of an ellipse is its director circle, but the orthoptic of a hyperbola is neither of its director circles.
$endgroup$
– amd
Dec 7 '18 at 9:20
$begingroup$
Look, I googled and I got this Wiki: In geometry, the director circle of an ellipse or hyperbola is a circle consisting of all points where two perpendicular tangent lines to the ellipse or hyperbola cross each other. And Orthoptic of a hyperbola as per wiki" The orthoptic of a hyperbola x^2/a^2 − y^2/b^2 = 1, a > b, is the circle x^2 + y^2 = a^2 − b^2 (in case of a ≤ b there are no orthogonal tangents, see below)". And , that is the director circle of the hyperbola. Please elaborate.
$endgroup$
– Sarthak Rout
Dec 7 '18 at 9:29
$begingroup$
Look, I googled and I got this Wiki: In geometry, the director circle of an ellipse or hyperbola is a circle consisting of all points where two perpendicular tangent lines to the ellipse or hyperbola cross each other. And Orthoptic of a hyperbola as per wiki" The orthoptic of a hyperbola x^2/a^2 − y^2/b^2 = 1, a > b, is the circle x^2 + y^2 = a^2 − b^2 (in case of a ≤ b there are no orthogonal tangents, see below)". And , that is the director circle of the hyperbola. Please elaborate.
$endgroup$
– Sarthak Rout
Dec 7 '18 at 9:29
$begingroup$
There appear to be conflicting articles and terminology (not the first time). In en.wikipedia.org/wiki/Orthoptic_(geometry) a hyperbola’s orthoptic is pointedly not called its director circle; en.wikipedia.org/wiki/Hyperbola also avoids calling the orthoptic the director circle, but also uses the term “circular directrix” for the latter. Unlike the orthoptic, these circles exist for all hyperbolas, a useful trait if you’re going to use them for construction. A footnote suggests that the term “director circle” is used differently in German and English.
$endgroup$
– amd
Dec 7 '18 at 10:10
$begingroup$
There appear to be conflicting articles and terminology (not the first time). In en.wikipedia.org/wiki/Orthoptic_(geometry) a hyperbola’s orthoptic is pointedly not called its director circle; en.wikipedia.org/wiki/Hyperbola also avoids calling the orthoptic the director circle, but also uses the term “circular directrix” for the latter. Unlike the orthoptic, these circles exist for all hyperbolas, a useful trait if you’re going to use them for construction. A footnote suggests that the term “director circle” is used differently in German and English.
$endgroup$
– amd
Dec 7 '18 at 10:10
1
1
$begingroup$
At any rate, without further information or assumptions, I think that the best you can do here is to state an upper bound for the eccentricity.
$endgroup$
– amd
Dec 7 '18 at 10:11
$begingroup$
At any rate, without further information or assumptions, I think that the best you can do here is to state an upper bound for the eccentricity.
$endgroup$
– amd
Dec 7 '18 at 10:11
add a comment |
1 Answer
1
active
oldest
votes
$begingroup$
The given data are not enough to fix the hyperbola eccentricity. You can better understand that with a simpler example: suppose you are given $y=0$ as an asymptote and $x=a$ as tangent, then take $y=mx$ as the second asymptote (with $m$ any non-vanishing real number). The equation of a hyperbola having those two asymptotes and tangent to line $x=a$ can be easily found to be
$$y(y-mx)=-{a^2m^2over4}.$$
The eccentricity of the above hyperbola is
$$
e={sqrt2over m}sqrt{1+m^2-sqrt{1+m^2}},
$$
hence it can take any value between $1$ and $sqrt{2}$, depending on the value of $m$.
EDIT.
With a rotation and a translation, the above example can be adapted to your data. You may check that the hyperbolas of equation
$$
(5x-4y+5)left((4-5m)y-(5+4m)x-5+{25over4}mright)={9over64}m^2
$$
are all tangent to line $4x+5y-7=0$ and have line $5x-4y+5=0$ as asymptote, for any value of $m$. The eccentricities of these hyperbolas are given by the same formula as before.
$endgroup$
$begingroup$
I have edited the question. Please see, if you can arrive at a result.
$endgroup$
– Sarthak Rout
Dec 9 '18 at 15:52
$begingroup$
I don't see any relevant change in your question: without some other information you cannot find the eccentricity. I used different lines in the above example just to keep calculations easy, but you could do exactly the same reasoning with your data, and find the same result.
$endgroup$
– Aretino
Dec 9 '18 at 16:27
add a comment |
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$begingroup$
The given data are not enough to fix the hyperbola eccentricity. You can better understand that with a simpler example: suppose you are given $y=0$ as an asymptote and $x=a$ as tangent, then take $y=mx$ as the second asymptote (with $m$ any non-vanishing real number). The equation of a hyperbola having those two asymptotes and tangent to line $x=a$ can be easily found to be
$$y(y-mx)=-{a^2m^2over4}.$$
The eccentricity of the above hyperbola is
$$
e={sqrt2over m}sqrt{1+m^2-sqrt{1+m^2}},
$$
hence it can take any value between $1$ and $sqrt{2}$, depending on the value of $m$.
EDIT.
With a rotation and a translation, the above example can be adapted to your data. You may check that the hyperbolas of equation
$$
(5x-4y+5)left((4-5m)y-(5+4m)x-5+{25over4}mright)={9over64}m^2
$$
are all tangent to line $4x+5y-7=0$ and have line $5x-4y+5=0$ as asymptote, for any value of $m$. The eccentricities of these hyperbolas are given by the same formula as before.
$endgroup$
$begingroup$
I have edited the question. Please see, if you can arrive at a result.
$endgroup$
– Sarthak Rout
Dec 9 '18 at 15:52
$begingroup$
I don't see any relevant change in your question: without some other information you cannot find the eccentricity. I used different lines in the above example just to keep calculations easy, but you could do exactly the same reasoning with your data, and find the same result.
$endgroup$
– Aretino
Dec 9 '18 at 16:27
add a comment |
$begingroup$
The given data are not enough to fix the hyperbola eccentricity. You can better understand that with a simpler example: suppose you are given $y=0$ as an asymptote and $x=a$ as tangent, then take $y=mx$ as the second asymptote (with $m$ any non-vanishing real number). The equation of a hyperbola having those two asymptotes and tangent to line $x=a$ can be easily found to be
$$y(y-mx)=-{a^2m^2over4}.$$
The eccentricity of the above hyperbola is
$$
e={sqrt2over m}sqrt{1+m^2-sqrt{1+m^2}},
$$
hence it can take any value between $1$ and $sqrt{2}$, depending on the value of $m$.
EDIT.
With a rotation and a translation, the above example can be adapted to your data. You may check that the hyperbolas of equation
$$
(5x-4y+5)left((4-5m)y-(5+4m)x-5+{25over4}mright)={9over64}m^2
$$
are all tangent to line $4x+5y-7=0$ and have line $5x-4y+5=0$ as asymptote, for any value of $m$. The eccentricities of these hyperbolas are given by the same formula as before.
$endgroup$
$begingroup$
I have edited the question. Please see, if you can arrive at a result.
$endgroup$
– Sarthak Rout
Dec 9 '18 at 15:52
$begingroup$
I don't see any relevant change in your question: without some other information you cannot find the eccentricity. I used different lines in the above example just to keep calculations easy, but you could do exactly the same reasoning with your data, and find the same result.
$endgroup$
– Aretino
Dec 9 '18 at 16:27
add a comment |
$begingroup$
The given data are not enough to fix the hyperbola eccentricity. You can better understand that with a simpler example: suppose you are given $y=0$ as an asymptote and $x=a$ as tangent, then take $y=mx$ as the second asymptote (with $m$ any non-vanishing real number). The equation of a hyperbola having those two asymptotes and tangent to line $x=a$ can be easily found to be
$$y(y-mx)=-{a^2m^2over4}.$$
The eccentricity of the above hyperbola is
$$
e={sqrt2over m}sqrt{1+m^2-sqrt{1+m^2}},
$$
hence it can take any value between $1$ and $sqrt{2}$, depending on the value of $m$.
EDIT.
With a rotation and a translation, the above example can be adapted to your data. You may check that the hyperbolas of equation
$$
(5x-4y+5)left((4-5m)y-(5+4m)x-5+{25over4}mright)={9over64}m^2
$$
are all tangent to line $4x+5y-7=0$ and have line $5x-4y+5=0$ as asymptote, for any value of $m$. The eccentricities of these hyperbolas are given by the same formula as before.
$endgroup$
The given data are not enough to fix the hyperbola eccentricity. You can better understand that with a simpler example: suppose you are given $y=0$ as an asymptote and $x=a$ as tangent, then take $y=mx$ as the second asymptote (with $m$ any non-vanishing real number). The equation of a hyperbola having those two asymptotes and tangent to line $x=a$ can be easily found to be
$$y(y-mx)=-{a^2m^2over4}.$$
The eccentricity of the above hyperbola is
$$
e={sqrt2over m}sqrt{1+m^2-sqrt{1+m^2}},
$$
hence it can take any value between $1$ and $sqrt{2}$, depending on the value of $m$.
EDIT.
With a rotation and a translation, the above example can be adapted to your data. You may check that the hyperbolas of equation
$$
(5x-4y+5)left((4-5m)y-(5+4m)x-5+{25over4}mright)={9over64}m^2
$$
are all tangent to line $4x+5y-7=0$ and have line $5x-4y+5=0$ as asymptote, for any value of $m$. The eccentricities of these hyperbolas are given by the same formula as before.
edited Dec 10 '18 at 13:41
answered Dec 8 '18 at 17:07
AretinoAretino
23.5k21443
23.5k21443
$begingroup$
I have edited the question. Please see, if you can arrive at a result.
$endgroup$
– Sarthak Rout
Dec 9 '18 at 15:52
$begingroup$
I don't see any relevant change in your question: without some other information you cannot find the eccentricity. I used different lines in the above example just to keep calculations easy, but you could do exactly the same reasoning with your data, and find the same result.
$endgroup$
– Aretino
Dec 9 '18 at 16:27
add a comment |
$begingroup$
I have edited the question. Please see, if you can arrive at a result.
$endgroup$
– Sarthak Rout
Dec 9 '18 at 15:52
$begingroup$
I don't see any relevant change in your question: without some other information you cannot find the eccentricity. I used different lines in the above example just to keep calculations easy, but you could do exactly the same reasoning with your data, and find the same result.
$endgroup$
– Aretino
Dec 9 '18 at 16:27
$begingroup$
I have edited the question. Please see, if you can arrive at a result.
$endgroup$
– Sarthak Rout
Dec 9 '18 at 15:52
$begingroup$
I have edited the question. Please see, if you can arrive at a result.
$endgroup$
– Sarthak Rout
Dec 9 '18 at 15:52
$begingroup$
I don't see any relevant change in your question: without some other information you cannot find the eccentricity. I used different lines in the above example just to keep calculations easy, but you could do exactly the same reasoning with your data, and find the same result.
$endgroup$
– Aretino
Dec 9 '18 at 16:27
$begingroup$
I don't see any relevant change in your question: without some other information you cannot find the eccentricity. I used different lines in the above example just to keep calculations easy, but you could do exactly the same reasoning with your data, and find the same result.
$endgroup$
– Aretino
Dec 9 '18 at 16:27
add a comment |
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$begingroup$
The orthoptic for an ellipse and a hyperbola is its director circle. Please google 'director circle' .
$endgroup$
– Sarthak Rout
Dec 7 '18 at 9:10
$begingroup$
Google “orthoptic” and “director circle” yourself. The orthoptic of an ellipse is its director circle, but the orthoptic of a hyperbola is neither of its director circles.
$endgroup$
– amd
Dec 7 '18 at 9:20
$begingroup$
Look, I googled and I got this Wiki: In geometry, the director circle of an ellipse or hyperbola is a circle consisting of all points where two perpendicular tangent lines to the ellipse or hyperbola cross each other. And Orthoptic of a hyperbola as per wiki" The orthoptic of a hyperbola x^2/a^2 − y^2/b^2 = 1, a > b, is the circle x^2 + y^2 = a^2 − b^2 (in case of a ≤ b there are no orthogonal tangents, see below)". And , that is the director circle of the hyperbola. Please elaborate.
$endgroup$
– Sarthak Rout
Dec 7 '18 at 9:29
$begingroup$
There appear to be conflicting articles and terminology (not the first time). In en.wikipedia.org/wiki/Orthoptic_(geometry) a hyperbola’s orthoptic is pointedly not called its director circle; en.wikipedia.org/wiki/Hyperbola also avoids calling the orthoptic the director circle, but also uses the term “circular directrix” for the latter. Unlike the orthoptic, these circles exist for all hyperbolas, a useful trait if you’re going to use them for construction. A footnote suggests that the term “director circle” is used differently in German and English.
$endgroup$
– amd
Dec 7 '18 at 10:10
1
$begingroup$
At any rate, without further information or assumptions, I think that the best you can do here is to state an upper bound for the eccentricity.
$endgroup$
– amd
Dec 7 '18 at 10:11