Finding point of intersection using cartesian equation?












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$begingroup$



L1 is defined by $ dfrac{x+1}{2} = dfrac{y-3}{3} = 1-z$



So we can write this as $((2t-1), (3t+3), (1-t)) = r $



L2 passes through $(5,4,2)$ and intersects with L1 at right angles.




I am asked to determine the point of intersections between those two lines.



I have tried to find the dot product of the directional vector of L1 and another directional vector (x,y,z)
So I got this $2x+3y-z = 0$ and said that $ x = 3, y=2$ and $ z=12$



So now L2 has the following equation
$ r = ((5+3t), (4+2t), (2+12t))$
However when i equate L1 and L2 to find $t$. The equations aren't satisfied, meaning that $t$ isn't common.










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  • $begingroup$
    You can't just assume $x=3,y=2,z=12$, because there are infinitely many vectors perpendicular to $(2,3,-1)$.
    $endgroup$
    – Shubham Johri
    Jan 9 at 18:23
















0












$begingroup$



L1 is defined by $ dfrac{x+1}{2} = dfrac{y-3}{3} = 1-z$



So we can write this as $((2t-1), (3t+3), (1-t)) = r $



L2 passes through $(5,4,2)$ and intersects with L1 at right angles.




I am asked to determine the point of intersections between those two lines.



I have tried to find the dot product of the directional vector of L1 and another directional vector (x,y,z)
So I got this $2x+3y-z = 0$ and said that $ x = 3, y=2$ and $ z=12$



So now L2 has the following equation
$ r = ((5+3t), (4+2t), (2+12t))$
However when i equate L1 and L2 to find $t$. The equations aren't satisfied, meaning that $t$ isn't common.










share|cite|improve this question









$endgroup$












  • $begingroup$
    You can't just assume $x=3,y=2,z=12$, because there are infinitely many vectors perpendicular to $(2,3,-1)$.
    $endgroup$
    – Shubham Johri
    Jan 9 at 18:23














0












0








0





$begingroup$



L1 is defined by $ dfrac{x+1}{2} = dfrac{y-3}{3} = 1-z$



So we can write this as $((2t-1), (3t+3), (1-t)) = r $



L2 passes through $(5,4,2)$ and intersects with L1 at right angles.




I am asked to determine the point of intersections between those two lines.



I have tried to find the dot product of the directional vector of L1 and another directional vector (x,y,z)
So I got this $2x+3y-z = 0$ and said that $ x = 3, y=2$ and $ z=12$



So now L2 has the following equation
$ r = ((5+3t), (4+2t), (2+12t))$
However when i equate L1 and L2 to find $t$. The equations aren't satisfied, meaning that $t$ isn't common.










share|cite|improve this question









$endgroup$





L1 is defined by $ dfrac{x+1}{2} = dfrac{y-3}{3} = 1-z$



So we can write this as $((2t-1), (3t+3), (1-t)) = r $



L2 passes through $(5,4,2)$ and intersects with L1 at right angles.




I am asked to determine the point of intersections between those two lines.



I have tried to find the dot product of the directional vector of L1 and another directional vector (x,y,z)
So I got this $2x+3y-z = 0$ and said that $ x = 3, y=2$ and $ z=12$



So now L2 has the following equation
$ r = ((5+3t), (4+2t), (2+12t))$
However when i equate L1 and L2 to find $t$. The equations aren't satisfied, meaning that $t$ isn't common.







vectors






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asked Jan 9 at 18:06









user154844user154844

33




33












  • $begingroup$
    You can't just assume $x=3,y=2,z=12$, because there are infinitely many vectors perpendicular to $(2,3,-1)$.
    $endgroup$
    – Shubham Johri
    Jan 9 at 18:23


















  • $begingroup$
    You can't just assume $x=3,y=2,z=12$, because there are infinitely many vectors perpendicular to $(2,3,-1)$.
    $endgroup$
    – Shubham Johri
    Jan 9 at 18:23
















$begingroup$
You can't just assume $x=3,y=2,z=12$, because there are infinitely many vectors perpendicular to $(2,3,-1)$.
$endgroup$
– Shubham Johri
Jan 9 at 18:23




$begingroup$
You can't just assume $x=3,y=2,z=12$, because there are infinitely many vectors perpendicular to $(2,3,-1)$.
$endgroup$
– Shubham Johri
Jan 9 at 18:23










2 Answers
2






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$begingroup$

The point of intersection lies on $L_1$, so we can express it as $P(2t-1,3t+3,1-t)$ for some $tinBbb R$. We require that the vector from $Pto(5,4,2)$ be orthogonal to the vector $(2,3,-1)$, which is colinear with the line. That is,$$(2t-1,3t+3,1-t)to(5,4,2)perp(2,3,-1)$$This implies,$$(2t-6,3t-1,-1-t)cdot(2,3,-1)=0$$giving the value of $t=1$ and the required point as $(1,6,0)$.






share|cite|improve this answer









$endgroup$





















    0












    $begingroup$

    Let $L_2$ $$vec{x}=[5,4,2]+s[a_x,a_y,a_z]$$
    Then we have the condition $$2a_x+3a_y+4a_z=0$$ (by the dot-product)
    and the system
    $$2t-sa_x=6$$
    $$3t-sa_y=1$$
    $$-t-sa_z=1$$
    Can you solve this?






    share|cite|improve this answer









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      2 Answers
      2






      active

      oldest

      votes








      2 Answers
      2






      active

      oldest

      votes









      active

      oldest

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      active

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      0












      $begingroup$

      The point of intersection lies on $L_1$, so we can express it as $P(2t-1,3t+3,1-t)$ for some $tinBbb R$. We require that the vector from $Pto(5,4,2)$ be orthogonal to the vector $(2,3,-1)$, which is colinear with the line. That is,$$(2t-1,3t+3,1-t)to(5,4,2)perp(2,3,-1)$$This implies,$$(2t-6,3t-1,-1-t)cdot(2,3,-1)=0$$giving the value of $t=1$ and the required point as $(1,6,0)$.






      share|cite|improve this answer









      $endgroup$


















        0












        $begingroup$

        The point of intersection lies on $L_1$, so we can express it as $P(2t-1,3t+3,1-t)$ for some $tinBbb R$. We require that the vector from $Pto(5,4,2)$ be orthogonal to the vector $(2,3,-1)$, which is colinear with the line. That is,$$(2t-1,3t+3,1-t)to(5,4,2)perp(2,3,-1)$$This implies,$$(2t-6,3t-1,-1-t)cdot(2,3,-1)=0$$giving the value of $t=1$ and the required point as $(1,6,0)$.






        share|cite|improve this answer









        $endgroup$
















          0












          0








          0





          $begingroup$

          The point of intersection lies on $L_1$, so we can express it as $P(2t-1,3t+3,1-t)$ for some $tinBbb R$. We require that the vector from $Pto(5,4,2)$ be orthogonal to the vector $(2,3,-1)$, which is colinear with the line. That is,$$(2t-1,3t+3,1-t)to(5,4,2)perp(2,3,-1)$$This implies,$$(2t-6,3t-1,-1-t)cdot(2,3,-1)=0$$giving the value of $t=1$ and the required point as $(1,6,0)$.






          share|cite|improve this answer









          $endgroup$



          The point of intersection lies on $L_1$, so we can express it as $P(2t-1,3t+3,1-t)$ for some $tinBbb R$. We require that the vector from $Pto(5,4,2)$ be orthogonal to the vector $(2,3,-1)$, which is colinear with the line. That is,$$(2t-1,3t+3,1-t)to(5,4,2)perp(2,3,-1)$$This implies,$$(2t-6,3t-1,-1-t)cdot(2,3,-1)=0$$giving the value of $t=1$ and the required point as $(1,6,0)$.







          share|cite|improve this answer












          share|cite|improve this answer



          share|cite|improve this answer










          answered Jan 9 at 18:18









          Shubham JohriShubham Johri

          4,760717




          4,760717























              0












              $begingroup$

              Let $L_2$ $$vec{x}=[5,4,2]+s[a_x,a_y,a_z]$$
              Then we have the condition $$2a_x+3a_y+4a_z=0$$ (by the dot-product)
              and the system
              $$2t-sa_x=6$$
              $$3t-sa_y=1$$
              $$-t-sa_z=1$$
              Can you solve this?






              share|cite|improve this answer









              $endgroup$


















                0












                $begingroup$

                Let $L_2$ $$vec{x}=[5,4,2]+s[a_x,a_y,a_z]$$
                Then we have the condition $$2a_x+3a_y+4a_z=0$$ (by the dot-product)
                and the system
                $$2t-sa_x=6$$
                $$3t-sa_y=1$$
                $$-t-sa_z=1$$
                Can you solve this?






                share|cite|improve this answer









                $endgroup$
















                  0












                  0








                  0





                  $begingroup$

                  Let $L_2$ $$vec{x}=[5,4,2]+s[a_x,a_y,a_z]$$
                  Then we have the condition $$2a_x+3a_y+4a_z=0$$ (by the dot-product)
                  and the system
                  $$2t-sa_x=6$$
                  $$3t-sa_y=1$$
                  $$-t-sa_z=1$$
                  Can you solve this?






                  share|cite|improve this answer









                  $endgroup$



                  Let $L_2$ $$vec{x}=[5,4,2]+s[a_x,a_y,a_z]$$
                  Then we have the condition $$2a_x+3a_y+4a_z=0$$ (by the dot-product)
                  and the system
                  $$2t-sa_x=6$$
                  $$3t-sa_y=1$$
                  $$-t-sa_z=1$$
                  Can you solve this?







                  share|cite|improve this answer












                  share|cite|improve this answer



                  share|cite|improve this answer










                  answered Jan 9 at 18:18









                  Dr. Sonnhard GraubnerDr. Sonnhard Graubner

                  74k42865




                  74k42865






























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