Line through a a given point in the first quadrant of the coordinate plane to form a triangle [closed]












0












$begingroup$


Consider a straight line with negative gradient passing through the positive quadrant (where all co-ordinates are positive, or the first quadrant) of the co-ordinate plane and intercepting the $x$ and $y$ axes to form a triangle with them.



Which points in the positive quadrant can the line pass through such that the triangle always has area $2$?



I've considered the point $(1,1)$ and formed an equation in terms of the rectangle made by the point and the two triangles either side of it. My hypothesis is that anything right of $(1,1)$ doesn't work










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closed as off-topic by Namaste, KReiser, Leucippus, Cesareo, José Carlos Santos Jan 7 at 8:39


This question appears to be off-topic. The users who voted to close gave this specific reason:


  • "This question is missing context or other details: Please provide additional context, which ideally explains why the question is relevant to you and our community. Some forms of context include: background and motivation, relevant definitions, source, possible strategies, your current progress, why the question is interesting or important, etc." – Namaste, KReiser, Leucippus, Cesareo, José Carlos Santos

If this question can be reworded to fit the rules in the help center, please edit the question.
















  • $begingroup$
    hi, what have you tried so far?
    $endgroup$
    – Siong Thye Goh
    Jan 7 at 1:33










  • $begingroup$
    Edited in a little
    $endgroup$
    – user491842
    Jan 7 at 1:39










  • $begingroup$
    any points (0,2x) and (x,0)
    $endgroup$
    – user29418
    Jan 7 at 1:40










  • $begingroup$
    A line going through $(1,1)$ and intersecting both the $x$ and $y$ axis in the first quadrant will have points on the right of $(1,1)$ (the point will just have lower $y$ coordinates)
    $endgroup$
    – Andrei
    Jan 7 at 1:43
















0












$begingroup$


Consider a straight line with negative gradient passing through the positive quadrant (where all co-ordinates are positive, or the first quadrant) of the co-ordinate plane and intercepting the $x$ and $y$ axes to form a triangle with them.



Which points in the positive quadrant can the line pass through such that the triangle always has area $2$?



I've considered the point $(1,1)$ and formed an equation in terms of the rectangle made by the point and the two triangles either side of it. My hypothesis is that anything right of $(1,1)$ doesn't work










share|cite|improve this question











$endgroup$



closed as off-topic by Namaste, KReiser, Leucippus, Cesareo, José Carlos Santos Jan 7 at 8:39


This question appears to be off-topic. The users who voted to close gave this specific reason:


  • "This question is missing context or other details: Please provide additional context, which ideally explains why the question is relevant to you and our community. Some forms of context include: background and motivation, relevant definitions, source, possible strategies, your current progress, why the question is interesting or important, etc." – Namaste, KReiser, Leucippus, Cesareo, José Carlos Santos

If this question can be reworded to fit the rules in the help center, please edit the question.
















  • $begingroup$
    hi, what have you tried so far?
    $endgroup$
    – Siong Thye Goh
    Jan 7 at 1:33










  • $begingroup$
    Edited in a little
    $endgroup$
    – user491842
    Jan 7 at 1:39










  • $begingroup$
    any points (0,2x) and (x,0)
    $endgroup$
    – user29418
    Jan 7 at 1:40










  • $begingroup$
    A line going through $(1,1)$ and intersecting both the $x$ and $y$ axis in the first quadrant will have points on the right of $(1,1)$ (the point will just have lower $y$ coordinates)
    $endgroup$
    – Andrei
    Jan 7 at 1:43














0












0








0





$begingroup$


Consider a straight line with negative gradient passing through the positive quadrant (where all co-ordinates are positive, or the first quadrant) of the co-ordinate plane and intercepting the $x$ and $y$ axes to form a triangle with them.



Which points in the positive quadrant can the line pass through such that the triangle always has area $2$?



I've considered the point $(1,1)$ and formed an equation in terms of the rectangle made by the point and the two triangles either side of it. My hypothesis is that anything right of $(1,1)$ doesn't work










share|cite|improve this question











$endgroup$




Consider a straight line with negative gradient passing through the positive quadrant (where all co-ordinates are positive, or the first quadrant) of the co-ordinate plane and intercepting the $x$ and $y$ axes to form a triangle with them.



Which points in the positive quadrant can the line pass through such that the triangle always has area $2$?



I've considered the point $(1,1)$ and formed an equation in terms of the rectangle made by the point and the two triangles either side of it. My hypothesis is that anything right of $(1,1)$ doesn't work







geometry






share|cite|improve this question















share|cite|improve this question













share|cite|improve this question




share|cite|improve this question








edited Jan 7 at 1:41









Andrei

13.7k21230




13.7k21230










asked Jan 7 at 1:30









user491842user491842

62




62




closed as off-topic by Namaste, KReiser, Leucippus, Cesareo, José Carlos Santos Jan 7 at 8:39


This question appears to be off-topic. The users who voted to close gave this specific reason:


  • "This question is missing context or other details: Please provide additional context, which ideally explains why the question is relevant to you and our community. Some forms of context include: background and motivation, relevant definitions, source, possible strategies, your current progress, why the question is interesting or important, etc." – Namaste, KReiser, Leucippus, Cesareo, José Carlos Santos

If this question can be reworded to fit the rules in the help center, please edit the question.







closed as off-topic by Namaste, KReiser, Leucippus, Cesareo, José Carlos Santos Jan 7 at 8:39


This question appears to be off-topic. The users who voted to close gave this specific reason:


  • "This question is missing context or other details: Please provide additional context, which ideally explains why the question is relevant to you and our community. Some forms of context include: background and motivation, relevant definitions, source, possible strategies, your current progress, why the question is interesting or important, etc." – Namaste, KReiser, Leucippus, Cesareo, José Carlos Santos

If this question can be reworded to fit the rules in the help center, please edit the question.












  • $begingroup$
    hi, what have you tried so far?
    $endgroup$
    – Siong Thye Goh
    Jan 7 at 1:33










  • $begingroup$
    Edited in a little
    $endgroup$
    – user491842
    Jan 7 at 1:39










  • $begingroup$
    any points (0,2x) and (x,0)
    $endgroup$
    – user29418
    Jan 7 at 1:40










  • $begingroup$
    A line going through $(1,1)$ and intersecting both the $x$ and $y$ axis in the first quadrant will have points on the right of $(1,1)$ (the point will just have lower $y$ coordinates)
    $endgroup$
    – Andrei
    Jan 7 at 1:43


















  • $begingroup$
    hi, what have you tried so far?
    $endgroup$
    – Siong Thye Goh
    Jan 7 at 1:33










  • $begingroup$
    Edited in a little
    $endgroup$
    – user491842
    Jan 7 at 1:39










  • $begingroup$
    any points (0,2x) and (x,0)
    $endgroup$
    – user29418
    Jan 7 at 1:40










  • $begingroup$
    A line going through $(1,1)$ and intersecting both the $x$ and $y$ axis in the first quadrant will have points on the right of $(1,1)$ (the point will just have lower $y$ coordinates)
    $endgroup$
    – Andrei
    Jan 7 at 1:43
















$begingroup$
hi, what have you tried so far?
$endgroup$
– Siong Thye Goh
Jan 7 at 1:33




$begingroup$
hi, what have you tried so far?
$endgroup$
– Siong Thye Goh
Jan 7 at 1:33












$begingroup$
Edited in a little
$endgroup$
– user491842
Jan 7 at 1:39




$begingroup$
Edited in a little
$endgroup$
– user491842
Jan 7 at 1:39












$begingroup$
any points (0,2x) and (x,0)
$endgroup$
– user29418
Jan 7 at 1:40




$begingroup$
any points (0,2x) and (x,0)
$endgroup$
– user29418
Jan 7 at 1:40












$begingroup$
A line going through $(1,1)$ and intersecting both the $x$ and $y$ axis in the first quadrant will have points on the right of $(1,1)$ (the point will just have lower $y$ coordinates)
$endgroup$
– Andrei
Jan 7 at 1:43




$begingroup$
A line going through $(1,1)$ and intersecting both the $x$ and $y$ axis in the first quadrant will have points on the right of $(1,1)$ (the point will just have lower $y$ coordinates)
$endgroup$
– Andrei
Jan 7 at 1:43










2 Answers
2






active

oldest

votes


















2












$begingroup$

Guide:



Suppose the gradient is $m$ and the $x$-intercept is $x$, then the $y$ intercept is $-mx$.



That is we want to have $$frac12cdot xcdot (-mx) = 2$$



Hence solving for $x$ in terms of $m$ should fully determine the line.






share|cite|improve this answer









$endgroup$





















    0












    $begingroup$

    The equation of a line in the plane, with slope $-m$ can be written as $$y=-mx+b$$To get the condition to have the area $2$, we need to calculate the intersection with the axes. If $x=0$, you get $y=b$. If $y=0$, you get $$x=frac bm$$
    The area of the triangle is then $$2=frac 12 bfrac bm$$which yields $$b=2sqrt m$$
    Going back to the original equation $$y=-mx+2sqrt m$$
    Now let's suppose that I have a point $(x_0,y_0)$ on such line. What would happen if I keep $x_0$ constant, and I want to either increase or decrease $y_0$? Can I find a different $m$? Otherwise saying, given $x_0$, for what values of $y_0$ can I find a solution for the following equation: $$y_0=-mx_0+2sqrt m$$We can write this as a quadratic equation in $X=sqrt m$
    $$x_0X^2-2X+y_0=0$$
    To have a real solution, we need the discriminant to be positive, so $$1-x_0y_0ge 0$$ or $$x_0y_0le 1$$
    What it means that any point that lies in the first quadrant below the hyperbola $xy=1$ is part of at least one line such that the intersections with the axis form a triangle with area $2$.






    share|cite|improve this answer









    $endgroup$




















      2 Answers
      2






      active

      oldest

      votes








      2 Answers
      2






      active

      oldest

      votes









      active

      oldest

      votes






      active

      oldest

      votes









      2












      $begingroup$

      Guide:



      Suppose the gradient is $m$ and the $x$-intercept is $x$, then the $y$ intercept is $-mx$.



      That is we want to have $$frac12cdot xcdot (-mx) = 2$$



      Hence solving for $x$ in terms of $m$ should fully determine the line.






      share|cite|improve this answer









      $endgroup$


















        2












        $begingroup$

        Guide:



        Suppose the gradient is $m$ and the $x$-intercept is $x$, then the $y$ intercept is $-mx$.



        That is we want to have $$frac12cdot xcdot (-mx) = 2$$



        Hence solving for $x$ in terms of $m$ should fully determine the line.






        share|cite|improve this answer









        $endgroup$
















          2












          2








          2





          $begingroup$

          Guide:



          Suppose the gradient is $m$ and the $x$-intercept is $x$, then the $y$ intercept is $-mx$.



          That is we want to have $$frac12cdot xcdot (-mx) = 2$$



          Hence solving for $x$ in terms of $m$ should fully determine the line.






          share|cite|improve this answer









          $endgroup$



          Guide:



          Suppose the gradient is $m$ and the $x$-intercept is $x$, then the $y$ intercept is $-mx$.



          That is we want to have $$frac12cdot xcdot (-mx) = 2$$



          Hence solving for $x$ in terms of $m$ should fully determine the line.







          share|cite|improve this answer












          share|cite|improve this answer



          share|cite|improve this answer










          answered Jan 7 at 1:42









          Siong Thye GohSiong Thye Goh

          104k1468120




          104k1468120























              0












              $begingroup$

              The equation of a line in the plane, with slope $-m$ can be written as $$y=-mx+b$$To get the condition to have the area $2$, we need to calculate the intersection with the axes. If $x=0$, you get $y=b$. If $y=0$, you get $$x=frac bm$$
              The area of the triangle is then $$2=frac 12 bfrac bm$$which yields $$b=2sqrt m$$
              Going back to the original equation $$y=-mx+2sqrt m$$
              Now let's suppose that I have a point $(x_0,y_0)$ on such line. What would happen if I keep $x_0$ constant, and I want to either increase or decrease $y_0$? Can I find a different $m$? Otherwise saying, given $x_0$, for what values of $y_0$ can I find a solution for the following equation: $$y_0=-mx_0+2sqrt m$$We can write this as a quadratic equation in $X=sqrt m$
              $$x_0X^2-2X+y_0=0$$
              To have a real solution, we need the discriminant to be positive, so $$1-x_0y_0ge 0$$ or $$x_0y_0le 1$$
              What it means that any point that lies in the first quadrant below the hyperbola $xy=1$ is part of at least one line such that the intersections with the axis form a triangle with area $2$.






              share|cite|improve this answer









              $endgroup$


















                0












                $begingroup$

                The equation of a line in the plane, with slope $-m$ can be written as $$y=-mx+b$$To get the condition to have the area $2$, we need to calculate the intersection with the axes. If $x=0$, you get $y=b$. If $y=0$, you get $$x=frac bm$$
                The area of the triangle is then $$2=frac 12 bfrac bm$$which yields $$b=2sqrt m$$
                Going back to the original equation $$y=-mx+2sqrt m$$
                Now let's suppose that I have a point $(x_0,y_0)$ on such line. What would happen if I keep $x_0$ constant, and I want to either increase or decrease $y_0$? Can I find a different $m$? Otherwise saying, given $x_0$, for what values of $y_0$ can I find a solution for the following equation: $$y_0=-mx_0+2sqrt m$$We can write this as a quadratic equation in $X=sqrt m$
                $$x_0X^2-2X+y_0=0$$
                To have a real solution, we need the discriminant to be positive, so $$1-x_0y_0ge 0$$ or $$x_0y_0le 1$$
                What it means that any point that lies in the first quadrant below the hyperbola $xy=1$ is part of at least one line such that the intersections with the axis form a triangle with area $2$.






                share|cite|improve this answer









                $endgroup$
















                  0












                  0








                  0





                  $begingroup$

                  The equation of a line in the plane, with slope $-m$ can be written as $$y=-mx+b$$To get the condition to have the area $2$, we need to calculate the intersection with the axes. If $x=0$, you get $y=b$. If $y=0$, you get $$x=frac bm$$
                  The area of the triangle is then $$2=frac 12 bfrac bm$$which yields $$b=2sqrt m$$
                  Going back to the original equation $$y=-mx+2sqrt m$$
                  Now let's suppose that I have a point $(x_0,y_0)$ on such line. What would happen if I keep $x_0$ constant, and I want to either increase or decrease $y_0$? Can I find a different $m$? Otherwise saying, given $x_0$, for what values of $y_0$ can I find a solution for the following equation: $$y_0=-mx_0+2sqrt m$$We can write this as a quadratic equation in $X=sqrt m$
                  $$x_0X^2-2X+y_0=0$$
                  To have a real solution, we need the discriminant to be positive, so $$1-x_0y_0ge 0$$ or $$x_0y_0le 1$$
                  What it means that any point that lies in the first quadrant below the hyperbola $xy=1$ is part of at least one line such that the intersections with the axis form a triangle with area $2$.






                  share|cite|improve this answer









                  $endgroup$



                  The equation of a line in the plane, with slope $-m$ can be written as $$y=-mx+b$$To get the condition to have the area $2$, we need to calculate the intersection with the axes. If $x=0$, you get $y=b$. If $y=0$, you get $$x=frac bm$$
                  The area of the triangle is then $$2=frac 12 bfrac bm$$which yields $$b=2sqrt m$$
                  Going back to the original equation $$y=-mx+2sqrt m$$
                  Now let's suppose that I have a point $(x_0,y_0)$ on such line. What would happen if I keep $x_0$ constant, and I want to either increase or decrease $y_0$? Can I find a different $m$? Otherwise saying, given $x_0$, for what values of $y_0$ can I find a solution for the following equation: $$y_0=-mx_0+2sqrt m$$We can write this as a quadratic equation in $X=sqrt m$
                  $$x_0X^2-2X+y_0=0$$
                  To have a real solution, we need the discriminant to be positive, so $$1-x_0y_0ge 0$$ or $$x_0y_0le 1$$
                  What it means that any point that lies in the first quadrant below the hyperbola $xy=1$ is part of at least one line such that the intersections with the axis form a triangle with area $2$.







                  share|cite|improve this answer












                  share|cite|improve this answer



                  share|cite|improve this answer










                  answered Jan 7 at 2:27









                  AndreiAndrei

                  13.7k21230




                  13.7k21230















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