This is a plane, not a line!

Geometry Level 2

What is the normal vector of the plane represented by

x 1 1 + y 2 2 + z 3 3 = 0 ? \dfrac{x-1}{1}+\dfrac{y-2}{2}+\dfrac{z-3}{3}=0 ?

( 6 , 3 , 2 ) (6,3,2) ( 2 , 3 , 6 ) (2,3,6) ( 1 , 2 , 3 ) (1,2,3) ( 3 , 2 , 1 ) (3,2,1)

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9 solutions

展豪 張
Apr 25, 2016

The equation can be rewritten as ( ( x , y , z ) ( 1 , 2 , 3 ) ) ( 1 , 1 2 , 1 3 ) = 0 ((x,y,z)-(1,2,3))\cdot(1,\dfrac 12,\dfrac 13)=0
which means that the plane passes through ( 1 , 2 , 3 ) (1,2,3) and ( 1 , 1 2 , 1 3 ) (1,\dfrac 12,\dfrac 13) is a normal vector.
6 ( 1 , 1 2 , 1 3 ) = ( 6 , 3 , 2 ) 6(1,\dfrac 12,\dfrac 13)=(6,3,2) is also a normal vector.

thanks helped alot

gidon kessler - 4 years ago
Sam Bealing
Apr 26, 2016

Multiplying through by 6 6 we get: 6 x 6 + 3 y 6 + 2 z 6 = 0 6 x + 3 y + 2 x = 18 6x-6+3y-6+2z-6=0 \Rightarrow 6x+3y+2x=18

A normal vector to the plane a x + b y + c z = d ax+by+cz=d is ( a , b , c ) (a,b,c) so the answer is:

( 6 , 3 , 2 ) \boxed{(6,3,2)}

Vijay Srinivas
Oct 14, 2017

This comes to 6(x-1) + 3(y-2) + 2(z-3) = 0. Hence, the normal vector will be (6,3,2), meeting the plane at point (1,2,3)

Badhan Das
Oct 10, 2017

6 ( x 1 ) + 3 ( y 2 ) + 2 ( z 3 ) 6 \frac{6(x-1) + 3(y-2) + 2(z-3)}{6} =0 so coefficient of x is 6, of y is 3 and of z is 2. so the normal vector will be (6,3,2).

Chang Liu
Feb 11, 2019

LCM is 6, Denom of 1 means 6, 2 means 3 and 3 means 2. Corresponding multipliers of x,y and z represents normal vector.

Doyel Sarkar
Nov 8, 2018

multiplying by 6, we get, 6(x-1)+3(y-2)+2(z-3)=0 or, 6x-6+3y-6+2z-6=o or, 6x+3y+2z=18

now, the normal vector will be (a,b,c) i.e, (6,3,2).

.... where does the magic number 6 come from?

Chris Ward - 2 years, 2 months ago

Y we multiply 6

poojadevi A - 2 years, 2 months ago
Aditya Ojha
Aug 19, 2020

taking the lcm of 1,2 and 3 we need to multiply x-1 by 6 y-2 by 3 and z-3 by 2 . then the denominator is sent to rhs and we get standard equation of plane from where we can find the normal vector

Supun Kandambige
Sep 7, 2018
  • a(x-x0)+b(y-y0)+c(z-z0)=0
  • where a=1
  • b=1/2
  • c=1/3
  • x0=1 y0=2 z0=3
  • so n=<1,1/2,1/3>
  • linear dependent of n is <6,3,2>

suppose we we write the general e question as 6x + 3y + 2z - 18 = 0 but the normal vector will be 6i + 3j + 2k and hence the coefficients of the normal vector will be (6,3,2)

isaac njau - 2 years, 2 months ago

Direction Ratio of given plane equal to DR's of normal of plane are 6,3,2

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