# The intersection between two lines

• Jan 30th 2011, 06:23 PM
Oiler
The intersection between two lines
Hi all, another vector related problem; I have two vectors x = s(1,2,1) and x = r(-6,2,2). I know they are orthogonal because their dot product is 0. But when i equate their components. i get s = -6r, 2s = 2r and s = 2r. Cannot figure out how to solve that one, should i have atleast one equation that does not contain on of the two variables? Thanks.

EDIT:
The only value of r and s that i can see satisfies both equations is 0.
• Jan 30th 2011, 06:31 PM
dwsmith
Quote:

Originally Posted by Oiler
Hi all, another vector related problem; I have two vectors x = s(1,2,1) and x = r(-6,2,2). I know they are orthogonal because their dot product is 0. But when i equate their components. i get s = -6r, 2s = 2r and s = 2r. Cannot figure out how to solve that one, should i have atleast one equation that does not contain on of the two variables? Thanks.

EDIT:
The only value of r and s that i can see satisfies both equations is 0.

Can you type out the question you verbatim?

I don't exactly understand what you are trying to accomplish.
• Jan 30th 2011, 06:51 PM
Oiler
hi dwsmith, the question is not out of the book. I was playing around with graphing software and wanted to find the intersection of those two vectors. Thanks for your constant help.
• Jan 30th 2011, 06:53 PM
dwsmith
Quote:

Originally Posted by Oiler
hi dwsmith, the question is not out of the book. I was playing around with graphing software and wanted to find the intersection of those two vectors. Thanks for your constant help.

Are r and s scalars? If so, are they positive or negative?
• Jan 30th 2011, 06:58 PM
Oiler
sorry wasn't clear, its two lines in vector form, in 3-space. x1 = s(1,2,1) and x2 = r(-6,2,2). I get them into parametric form and equate them. Just not sure on how to solve for x,y,z.