# Two Planes Intersecting

1. Jul 8, 2004

### StonedPanda

This is my post that I posted in the calculus discussion area, but I know that there are a few people here in the same class (and using the same book!) so it's probably beneficial to post it here too.

edit: go me! of course I forget to post the link lol! https://www.physicsforums.com/showthread.php?p=252564#post252564

I must have been :zzz: ! =p

2. Jul 9, 2004

### Gza

You need to find the normal vectors for both planes, and simply take the cross product of them to produce a vector parallel to the line that represents the planes' intersection. Then use some algebra to find a point common to both planes; and therefore on the line, and you have your line. Sorry if this didn't make any sense, it makes perfect sense in my head, but it's hard to determine if the same is true in words. And I think you should try to limit your posts to one section to keep the moderators happy.

3. Jul 9, 2004

### StonedPanda

Ahh ok.

I thought about it a little, and that makes sense. Like if my planes were X + Y + Z = 0 and 2X + Y + Z = 0 I'd set Z equal to zero, and then I'd get a zyztem of equations and the point I'd use would be (X,Y,0, right? That makes sense, thanks gza!

Anyway, do you have any answers to the other questions?

(I'll only post in one section from now on if it matters! =p)