Rectangular Coordinate Systems












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$begingroup$


Let $A(0,2)$ and $B(6,0).$ Find all points $P$ on the line $y = 4$ such that $APperp BP.$

(a) by slope

(b) by Pythagorean Theorem



I tried getting the midpoint which is $M=(3,1)$ and then I looked for the slope $m= -1/3$ and the inverse of slope $3$ to find the equation of the line perpendicular to the points $A$ and $B$ which is $y = 3x -8.$










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$endgroup$












  • $begingroup$
    I tried getting the midpoint which is M=(3,1) and then I looked for the slope m= -1/3 and the inverse of slope 3 to find the equation of the line perpendicular to the points A and B which is y = 3x -8
    $endgroup$
    – nomad09
    Sep 15 '16 at 3:49










  • $begingroup$
    There is no need for midpoint. The perpendicular need not be to the middle
    $endgroup$
    – N.S.JOHN
    Sep 15 '16 at 3:51










  • $begingroup$
    That's where I get lost. I tried using the coordinates (0,4) and the inverse slope 3.
    $endgroup$
    – nomad09
    Sep 15 '16 at 3:53
















0












$begingroup$


Let $A(0,2)$ and $B(6,0).$ Find all points $P$ on the line $y = 4$ such that $APperp BP.$

(a) by slope

(b) by Pythagorean Theorem



I tried getting the midpoint which is $M=(3,1)$ and then I looked for the slope $m= -1/3$ and the inverse of slope $3$ to find the equation of the line perpendicular to the points $A$ and $B$ which is $y = 3x -8.$










share|cite|improve this question











$endgroup$












  • $begingroup$
    I tried getting the midpoint which is M=(3,1) and then I looked for the slope m= -1/3 and the inverse of slope 3 to find the equation of the line perpendicular to the points A and B which is y = 3x -8
    $endgroup$
    – nomad09
    Sep 15 '16 at 3:49










  • $begingroup$
    There is no need for midpoint. The perpendicular need not be to the middle
    $endgroup$
    – N.S.JOHN
    Sep 15 '16 at 3:51










  • $begingroup$
    That's where I get lost. I tried using the coordinates (0,4) and the inverse slope 3.
    $endgroup$
    – nomad09
    Sep 15 '16 at 3:53














0












0








0





$begingroup$


Let $A(0,2)$ and $B(6,0).$ Find all points $P$ on the line $y = 4$ such that $APperp BP.$

(a) by slope

(b) by Pythagorean Theorem



I tried getting the midpoint which is $M=(3,1)$ and then I looked for the slope $m= -1/3$ and the inverse of slope $3$ to find the equation of the line perpendicular to the points $A$ and $B$ which is $y = 3x -8.$










share|cite|improve this question











$endgroup$




Let $A(0,2)$ and $B(6,0).$ Find all points $P$ on the line $y = 4$ such that $APperp BP.$

(a) by slope

(b) by Pythagorean Theorem



I tried getting the midpoint which is $M=(3,1)$ and then I looked for the slope $m= -1/3$ and the inverse of slope $3$ to find the equation of the line perpendicular to the points $A$ and $B$ which is $y = 3x -8.$







algebra-precalculus trigonometry slope






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edited Dec 10 '18 at 15:36









user376343

3,7883828




3,7883828










asked Sep 15 '16 at 3:45









nomad09nomad09

61




61












  • $begingroup$
    I tried getting the midpoint which is M=(3,1) and then I looked for the slope m= -1/3 and the inverse of slope 3 to find the equation of the line perpendicular to the points A and B which is y = 3x -8
    $endgroup$
    – nomad09
    Sep 15 '16 at 3:49










  • $begingroup$
    There is no need for midpoint. The perpendicular need not be to the middle
    $endgroup$
    – N.S.JOHN
    Sep 15 '16 at 3:51










  • $begingroup$
    That's where I get lost. I tried using the coordinates (0,4) and the inverse slope 3.
    $endgroup$
    – nomad09
    Sep 15 '16 at 3:53


















  • $begingroup$
    I tried getting the midpoint which is M=(3,1) and then I looked for the slope m= -1/3 and the inverse of slope 3 to find the equation of the line perpendicular to the points A and B which is y = 3x -8
    $endgroup$
    – nomad09
    Sep 15 '16 at 3:49










  • $begingroup$
    There is no need for midpoint. The perpendicular need not be to the middle
    $endgroup$
    – N.S.JOHN
    Sep 15 '16 at 3:51










  • $begingroup$
    That's where I get lost. I tried using the coordinates (0,4) and the inverse slope 3.
    $endgroup$
    – nomad09
    Sep 15 '16 at 3:53
















$begingroup$
I tried getting the midpoint which is M=(3,1) and then I looked for the slope m= -1/3 and the inverse of slope 3 to find the equation of the line perpendicular to the points A and B which is y = 3x -8
$endgroup$
– nomad09
Sep 15 '16 at 3:49




$begingroup$
I tried getting the midpoint which is M=(3,1) and then I looked for the slope m= -1/3 and the inverse of slope 3 to find the equation of the line perpendicular to the points A and B which is y = 3x -8
$endgroup$
– nomad09
Sep 15 '16 at 3:49












$begingroup$
There is no need for midpoint. The perpendicular need not be to the middle
$endgroup$
– N.S.JOHN
Sep 15 '16 at 3:51




$begingroup$
There is no need for midpoint. The perpendicular need not be to the middle
$endgroup$
– N.S.JOHN
Sep 15 '16 at 3:51












$begingroup$
That's where I get lost. I tried using the coordinates (0,4) and the inverse slope 3.
$endgroup$
– nomad09
Sep 15 '16 at 3:53




$begingroup$
That's where I get lost. I tried using the coordinates (0,4) and the inverse slope 3.
$endgroup$
– nomad09
Sep 15 '16 at 3:53










2 Answers
2






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oldest

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0












$begingroup$

Take P $(x,4)$ Find slope of AP and BP in terms of $x $.
Now use the relation between perpendicular slopes and equate and solve for $x $






share|cite|improve this answer









$endgroup$





















    0












    $begingroup$

    If $AP$ and $BP$ are perpendicular, that means they form a right angle and $AB$ is the hypotenuse of a right triangle. So you can use the distance formula to find the distance between $(0, 2)$ and $(p, 4)$ and the distance between $(6, 0)$ and $(p, 4)$. Plug these distances in to the Pythagorean Theorem to see if they make a right triangle.



    So we have these distances:

    $AB=sqrt{left(6-0right)^2+left(0-2right)^2}=sqrt{36+4}=sqrt{40}$

    $AP=sqrt{left(p-0right)^2+left(4-2right)^2}=sqrt{p^2+4}$

    $BP=sqrt{left(6-pright)^2+left(0-4right)^2}=sqrt{36-12p+p^2+16}=sqrt{p^2-12p+52}$



    Now we use the converse of the Pythagorean Theorem to see which values of $p$ (if any) make a right triangle. (This is the fun part because we make the square root symbols go away.)



    $left(sqrt{p^2-12p+52}right)^2+left(sqrt{p^2+4}right)^2=left(sqrt{40}right)^2$

    $p^2-12p+52+p^2+4=40$

    $2p^2-12p+56=40$

    $2p^2-12p+16=0$



    This quadratic equation is easy to factor:
    $2left(p^2-6p+8right)=0$

    $2left(p-2right)left(p-4right)=0$



    Thus we have $p=2$ or $p=4$. In the context of the problem, this means the points that make a right triangle (where $AP$ and $BP$ are perpendicular) are $(2,4)$ and $(4,4)$.






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      2 Answers
      2






      active

      oldest

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      2 Answers
      2






      active

      oldest

      votes









      active

      oldest

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      active

      oldest

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      0












      $begingroup$

      Take P $(x,4)$ Find slope of AP and BP in terms of $x $.
      Now use the relation between perpendicular slopes and equate and solve for $x $






      share|cite|improve this answer









      $endgroup$


















        0












        $begingroup$

        Take P $(x,4)$ Find slope of AP and BP in terms of $x $.
        Now use the relation between perpendicular slopes and equate and solve for $x $






        share|cite|improve this answer









        $endgroup$
















          0












          0








          0





          $begingroup$

          Take P $(x,4)$ Find slope of AP and BP in terms of $x $.
          Now use the relation between perpendicular slopes and equate and solve for $x $






          share|cite|improve this answer









          $endgroup$



          Take P $(x,4)$ Find slope of AP and BP in terms of $x $.
          Now use the relation between perpendicular slopes and equate and solve for $x $







          share|cite|improve this answer












          share|cite|improve this answer



          share|cite|improve this answer










          answered Sep 15 '16 at 3:57









          N.S.JOHNN.S.JOHN

          1,177620




          1,177620























              0












              $begingroup$

              If $AP$ and $BP$ are perpendicular, that means they form a right angle and $AB$ is the hypotenuse of a right triangle. So you can use the distance formula to find the distance between $(0, 2)$ and $(p, 4)$ and the distance between $(6, 0)$ and $(p, 4)$. Plug these distances in to the Pythagorean Theorem to see if they make a right triangle.



              So we have these distances:

              $AB=sqrt{left(6-0right)^2+left(0-2right)^2}=sqrt{36+4}=sqrt{40}$

              $AP=sqrt{left(p-0right)^2+left(4-2right)^2}=sqrt{p^2+4}$

              $BP=sqrt{left(6-pright)^2+left(0-4right)^2}=sqrt{36-12p+p^2+16}=sqrt{p^2-12p+52}$



              Now we use the converse of the Pythagorean Theorem to see which values of $p$ (if any) make a right triangle. (This is the fun part because we make the square root symbols go away.)



              $left(sqrt{p^2-12p+52}right)^2+left(sqrt{p^2+4}right)^2=left(sqrt{40}right)^2$

              $p^2-12p+52+p^2+4=40$

              $2p^2-12p+56=40$

              $2p^2-12p+16=0$



              This quadratic equation is easy to factor:
              $2left(p^2-6p+8right)=0$

              $2left(p-2right)left(p-4right)=0$



              Thus we have $p=2$ or $p=4$. In the context of the problem, this means the points that make a right triangle (where $AP$ and $BP$ are perpendicular) are $(2,4)$ and $(4,4)$.






              share|cite|improve this answer









              $endgroup$


















                0












                $begingroup$

                If $AP$ and $BP$ are perpendicular, that means they form a right angle and $AB$ is the hypotenuse of a right triangle. So you can use the distance formula to find the distance between $(0, 2)$ and $(p, 4)$ and the distance between $(6, 0)$ and $(p, 4)$. Plug these distances in to the Pythagorean Theorem to see if they make a right triangle.



                So we have these distances:

                $AB=sqrt{left(6-0right)^2+left(0-2right)^2}=sqrt{36+4}=sqrt{40}$

                $AP=sqrt{left(p-0right)^2+left(4-2right)^2}=sqrt{p^2+4}$

                $BP=sqrt{left(6-pright)^2+left(0-4right)^2}=sqrt{36-12p+p^2+16}=sqrt{p^2-12p+52}$



                Now we use the converse of the Pythagorean Theorem to see which values of $p$ (if any) make a right triangle. (This is the fun part because we make the square root symbols go away.)



                $left(sqrt{p^2-12p+52}right)^2+left(sqrt{p^2+4}right)^2=left(sqrt{40}right)^2$

                $p^2-12p+52+p^2+4=40$

                $2p^2-12p+56=40$

                $2p^2-12p+16=0$



                This quadratic equation is easy to factor:
                $2left(p^2-6p+8right)=0$

                $2left(p-2right)left(p-4right)=0$



                Thus we have $p=2$ or $p=4$. In the context of the problem, this means the points that make a right triangle (where $AP$ and $BP$ are perpendicular) are $(2,4)$ and $(4,4)$.






                share|cite|improve this answer









                $endgroup$
















                  0












                  0








                  0





                  $begingroup$

                  If $AP$ and $BP$ are perpendicular, that means they form a right angle and $AB$ is the hypotenuse of a right triangle. So you can use the distance formula to find the distance between $(0, 2)$ and $(p, 4)$ and the distance between $(6, 0)$ and $(p, 4)$. Plug these distances in to the Pythagorean Theorem to see if they make a right triangle.



                  So we have these distances:

                  $AB=sqrt{left(6-0right)^2+left(0-2right)^2}=sqrt{36+4}=sqrt{40}$

                  $AP=sqrt{left(p-0right)^2+left(4-2right)^2}=sqrt{p^2+4}$

                  $BP=sqrt{left(6-pright)^2+left(0-4right)^2}=sqrt{36-12p+p^2+16}=sqrt{p^2-12p+52}$



                  Now we use the converse of the Pythagorean Theorem to see which values of $p$ (if any) make a right triangle. (This is the fun part because we make the square root symbols go away.)



                  $left(sqrt{p^2-12p+52}right)^2+left(sqrt{p^2+4}right)^2=left(sqrt{40}right)^2$

                  $p^2-12p+52+p^2+4=40$

                  $2p^2-12p+56=40$

                  $2p^2-12p+16=0$



                  This quadratic equation is easy to factor:
                  $2left(p^2-6p+8right)=0$

                  $2left(p-2right)left(p-4right)=0$



                  Thus we have $p=2$ or $p=4$. In the context of the problem, this means the points that make a right triangle (where $AP$ and $BP$ are perpendicular) are $(2,4)$ and $(4,4)$.






                  share|cite|improve this answer









                  $endgroup$



                  If $AP$ and $BP$ are perpendicular, that means they form a right angle and $AB$ is the hypotenuse of a right triangle. So you can use the distance formula to find the distance between $(0, 2)$ and $(p, 4)$ and the distance between $(6, 0)$ and $(p, 4)$. Plug these distances in to the Pythagorean Theorem to see if they make a right triangle.



                  So we have these distances:

                  $AB=sqrt{left(6-0right)^2+left(0-2right)^2}=sqrt{36+4}=sqrt{40}$

                  $AP=sqrt{left(p-0right)^2+left(4-2right)^2}=sqrt{p^2+4}$

                  $BP=sqrt{left(6-pright)^2+left(0-4right)^2}=sqrt{36-12p+p^2+16}=sqrt{p^2-12p+52}$



                  Now we use the converse of the Pythagorean Theorem to see which values of $p$ (if any) make a right triangle. (This is the fun part because we make the square root symbols go away.)



                  $left(sqrt{p^2-12p+52}right)^2+left(sqrt{p^2+4}right)^2=left(sqrt{40}right)^2$

                  $p^2-12p+52+p^2+4=40$

                  $2p^2-12p+56=40$

                  $2p^2-12p+16=0$



                  This quadratic equation is easy to factor:
                  $2left(p^2-6p+8right)=0$

                  $2left(p-2right)left(p-4right)=0$



                  Thus we have $p=2$ or $p=4$. In the context of the problem, this means the points that make a right triangle (where $AP$ and $BP$ are perpendicular) are $(2,4)$ and $(4,4)$.







                  share|cite|improve this answer












                  share|cite|improve this answer



                  share|cite|improve this answer










                  answered Sep 16 '16 at 0:18









                  scottscott

                  1,459511




                  1,459511






























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