Home » Ask & Discuss » Mathematics. » Vectors « Back to Discussion

Vectors

New kid on the Block

Joined:	22 Mar 2008
Post:	24

24 Mar 2008 16:13:40 IST

0 People liked this

374

maths problem

None

let L be the line of intersection of the planes 2x+3y+z=1 and x+3y+2z=2.if L makes an angle with the positive x axis,then cos=.............

Share this article on:

Comments (3)

pinnacle

Hot goIITian

Joined: 16 Aug 2007

Posts: 176

24 Mar 2008 16:30:38 IST

Like 0 people liked this

Hmm
AIEEE 2007 ka sawal!
just form d equation of d line of intersection of two planes den DCs and den cos alpha....

For formin d strght line equationn 2x+3y+z-1= x+3y+2z-2=0

let d DCs of d line be a b and c
toh two equations ll be
2a+3b+c=0
and
a+3b+2c=0
dono ko solve karo
get the value of a b and c
den
for the points
LET z= 0
solve d equations
2x+3y=1
and
x+3y=2
get the points
though points arent required if u want d angle

Hopefully it cleared ur doubt

Rahul Raghavendra

Blazing goIITian

Joined: 9 Jan 2008

Posts: 843

24 Mar 2008 16:35:13 IST

Like 0 people liked this

Intersection of two planes gives a line

Thus , eqn of line L is;

$2x+3y+z-1-(x+3y+2z-2)=0\\\\ x-z+1=0\\\\$

It can be further represented as

$\frac{x-0}{1}=\frac{y-0}{0}=\frac{z-1}{1}\\\\$

Angle between xaxis and the line will be

$\cos{\alpha}=\frac{1}{\sqrt{2}}\\\\ \alpha=\frac{\pi}{4}$

pinnacle

Hot goIITian

Joined: 16 Aug 2007

Posts: 176

24 Mar 2008 16:38:28 IST

Like 0 people liked this

@ abv
Dude answer is 1/ root 3

Quick Reply

Reply

	Some HTML allowed.
	Keep your comments above the belt or risk having them deleted.
	Signup for a avatar to have your pictures show up by your comment
	If Members see a thread that violates the Posting Rules, bring it to the attention of the Moderator Team