Find 3D line equation in simplest form.












1














The line parallel to planes $-5x + y = 0$ and $x + 6y = 0,$ passes through the point $(3,0,2).$

My solution:.

Direction vector of the line: $v (x,y,z).$

Orthogonal vectors of planes: $;p_1(-5,1,0),; p_2(1,6,0).$
$v cdot p_1 = |v| cdot |p_1| cdot cos 90 = -5x + y = 0. tag 1$
$v cdot p_2 = |v| cdot |p_2| cdot cos 90 = x + 6y = 0. tag 2$

Solve $(1)(2) => x = 0, ;y = 0.$

But answer in my book is $v(6, 30, -1).$

What have I done wrong? Thanks!










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  • 2




    It looks like your book is using the planes $-5x+y=0$ and $x+6z=0$. Notice that the second equation has replaced $y$ by $z$.
    – Michael Burr
    Nov 29 '18 at 9:39












  • Your right. My eyes were fooled by my mind. It is caused by an interesting neurological phenomenon: BRAIN FILTERING.
    – Willy
    Dec 7 '18 at 9:06
















1














The line parallel to planes $-5x + y = 0$ and $x + 6y = 0,$ passes through the point $(3,0,2).$

My solution:.

Direction vector of the line: $v (x,y,z).$

Orthogonal vectors of planes: $;p_1(-5,1,0),; p_2(1,6,0).$
$v cdot p_1 = |v| cdot |p_1| cdot cos 90 = -5x + y = 0. tag 1$
$v cdot p_2 = |v| cdot |p_2| cdot cos 90 = x + 6y = 0. tag 2$

Solve $(1)(2) => x = 0, ;y = 0.$

But answer in my book is $v(6, 30, -1).$

What have I done wrong? Thanks!










share|cite|improve this question




















  • 2




    It looks like your book is using the planes $-5x+y=0$ and $x+6z=0$. Notice that the second equation has replaced $y$ by $z$.
    – Michael Burr
    Nov 29 '18 at 9:39












  • Your right. My eyes were fooled by my mind. It is caused by an interesting neurological phenomenon: BRAIN FILTERING.
    – Willy
    Dec 7 '18 at 9:06














1












1








1







The line parallel to planes $-5x + y = 0$ and $x + 6y = 0,$ passes through the point $(3,0,2).$

My solution:.

Direction vector of the line: $v (x,y,z).$

Orthogonal vectors of planes: $;p_1(-5,1,0),; p_2(1,6,0).$
$v cdot p_1 = |v| cdot |p_1| cdot cos 90 = -5x + y = 0. tag 1$
$v cdot p_2 = |v| cdot |p_2| cdot cos 90 = x + 6y = 0. tag 2$

Solve $(1)(2) => x = 0, ;y = 0.$

But answer in my book is $v(6, 30, -1).$

What have I done wrong? Thanks!










share|cite|improve this question















The line parallel to planes $-5x + y = 0$ and $x + 6y = 0,$ passes through the point $(3,0,2).$

My solution:.

Direction vector of the line: $v (x,y,z).$

Orthogonal vectors of planes: $;p_1(-5,1,0),; p_2(1,6,0).$
$v cdot p_1 = |v| cdot |p_1| cdot cos 90 = -5x + y = 0. tag 1$
$v cdot p_2 = |v| cdot |p_2| cdot cos 90 = x + 6y = 0. tag 2$

Solve $(1)(2) => x = 0, ;y = 0.$

But answer in my book is $v(6, 30, -1).$

What have I done wrong? Thanks!







geometry






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edited Nov 29 '18 at 10:08









user376343

2,9132823




2,9132823










asked Nov 29 '18 at 9:34









WillyWilly

414




414








  • 2




    It looks like your book is using the planes $-5x+y=0$ and $x+6z=0$. Notice that the second equation has replaced $y$ by $z$.
    – Michael Burr
    Nov 29 '18 at 9:39












  • Your right. My eyes were fooled by my mind. It is caused by an interesting neurological phenomenon: BRAIN FILTERING.
    – Willy
    Dec 7 '18 at 9:06














  • 2




    It looks like your book is using the planes $-5x+y=0$ and $x+6z=0$. Notice that the second equation has replaced $y$ by $z$.
    – Michael Burr
    Nov 29 '18 at 9:39












  • Your right. My eyes were fooled by my mind. It is caused by an interesting neurological phenomenon: BRAIN FILTERING.
    – Willy
    Dec 7 '18 at 9:06








2




2




It looks like your book is using the planes $-5x+y=0$ and $x+6z=0$. Notice that the second equation has replaced $y$ by $z$.
– Michael Burr
Nov 29 '18 at 9:39






It looks like your book is using the planes $-5x+y=0$ and $x+6z=0$. Notice that the second equation has replaced $y$ by $z$.
– Michael Burr
Nov 29 '18 at 9:39














Your right. My eyes were fooled by my mind. It is caused by an interesting neurological phenomenon: BRAIN FILTERING.
– Willy
Dec 7 '18 at 9:06




Your right. My eyes were fooled by my mind. It is caused by an interesting neurological phenomenon: BRAIN FILTERING.
– Willy
Dec 7 '18 at 9:06










1 Answer
1






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oldest

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1














Your solution is wrong. In fact$$v=p_1times p_2$$which shows the orthogonality therefore$$v=(-5hat i+hat j)times (hat i+6hat j)=-31 hat k$$hence the line is parallel to z-axis (which is expected) and the equation of the line would be$$begin{cases}x=3\y=0\z=tend{cases}$$






share|cite|improve this answer





















  • Thanks! Your answer & mine are both right. Alter solve(1), (2), find out v = (0,0,t), I can conclude the line equation like yours.
    – Willy
    Dec 4 '18 at 11:11










  • Nice! Good luck!!
    – Mostafa Ayaz
    Dec 4 '18 at 11:15











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1 Answer
1






active

oldest

votes








1 Answer
1






active

oldest

votes









active

oldest

votes






active

oldest

votes









1














Your solution is wrong. In fact$$v=p_1times p_2$$which shows the orthogonality therefore$$v=(-5hat i+hat j)times (hat i+6hat j)=-31 hat k$$hence the line is parallel to z-axis (which is expected) and the equation of the line would be$$begin{cases}x=3\y=0\z=tend{cases}$$






share|cite|improve this answer





















  • Thanks! Your answer & mine are both right. Alter solve(1), (2), find out v = (0,0,t), I can conclude the line equation like yours.
    – Willy
    Dec 4 '18 at 11:11










  • Nice! Good luck!!
    – Mostafa Ayaz
    Dec 4 '18 at 11:15
















1














Your solution is wrong. In fact$$v=p_1times p_2$$which shows the orthogonality therefore$$v=(-5hat i+hat j)times (hat i+6hat j)=-31 hat k$$hence the line is parallel to z-axis (which is expected) and the equation of the line would be$$begin{cases}x=3\y=0\z=tend{cases}$$






share|cite|improve this answer





















  • Thanks! Your answer & mine are both right. Alter solve(1), (2), find out v = (0,0,t), I can conclude the line equation like yours.
    – Willy
    Dec 4 '18 at 11:11










  • Nice! Good luck!!
    – Mostafa Ayaz
    Dec 4 '18 at 11:15














1












1








1






Your solution is wrong. In fact$$v=p_1times p_2$$which shows the orthogonality therefore$$v=(-5hat i+hat j)times (hat i+6hat j)=-31 hat k$$hence the line is parallel to z-axis (which is expected) and the equation of the line would be$$begin{cases}x=3\y=0\z=tend{cases}$$






share|cite|improve this answer












Your solution is wrong. In fact$$v=p_1times p_2$$which shows the orthogonality therefore$$v=(-5hat i+hat j)times (hat i+6hat j)=-31 hat k$$hence the line is parallel to z-axis (which is expected) and the equation of the line would be$$begin{cases}x=3\y=0\z=tend{cases}$$







share|cite|improve this answer












share|cite|improve this answer



share|cite|improve this answer










answered Nov 29 '18 at 9:56









Mostafa AyazMostafa Ayaz

14.1k3937




14.1k3937












  • Thanks! Your answer & mine are both right. Alter solve(1), (2), find out v = (0,0,t), I can conclude the line equation like yours.
    – Willy
    Dec 4 '18 at 11:11










  • Nice! Good luck!!
    – Mostafa Ayaz
    Dec 4 '18 at 11:15


















  • Thanks! Your answer & mine are both right. Alter solve(1), (2), find out v = (0,0,t), I can conclude the line equation like yours.
    – Willy
    Dec 4 '18 at 11:11










  • Nice! Good luck!!
    – Mostafa Ayaz
    Dec 4 '18 at 11:15
















Thanks! Your answer & mine are both right. Alter solve(1), (2), find out v = (0,0,t), I can conclude the line equation like yours.
– Willy
Dec 4 '18 at 11:11




Thanks! Your answer & mine are both right. Alter solve(1), (2), find out v = (0,0,t), I can conclude the line equation like yours.
– Willy
Dec 4 '18 at 11:11












Nice! Good luck!!
– Mostafa Ayaz
Dec 4 '18 at 11:15




Nice! Good luck!!
– Mostafa Ayaz
Dec 4 '18 at 11:15


















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