#### Archived

This topic is now archived and is closed to further replies.

# Line equation

This topic is 6312 days old which is more than the 365 day threshold we allow for new replies. Please post a new topic.

## Recommended Posts

I have two question: -how is represented the equation of a line in 3D? -how to find the equation of a line (in 3D) with 2 of her points? Thanks.

##### Share on other sites
I suppose that line equation in 3d is little diffrerent from 2d.
Say in 2D the line is y=ax+b right?
So, in 3D it should be an expression like a structure
y=ax+b
y=qz+c
x=tz+u
or something like that..

##### Share on other sites
in 3d a line is the intersection of two planes.
You can also define it by a vector and a point I think.

-* So many things to do, so little time to spend. *-

##### Share on other sites
OK, let''s try it in parametric vector form.
P1 and P2 are to points on the line, t is the parameter (a real number). Then any point X on the line satisfies the following equation:
X = P1 + t * (P2 - P1)

So here we''ve got a line equation in R3 (this form works in any dimension, whereas the form y = kx + d only works in 2D. In 3D you can write the plane equation in a similar form, but not the line equation).

##### Share on other sites
Thanks everybody!!

1. 1
2. 2
Rutin
21
3. 3
4. 4
frob
17
5. 5

• 9
• 12
• 9
• 33
• 13
• ### Forum Statistics

• Total Topics
632594
• Total Posts
3007260

×