# Thread: paralell to xy, yz, xz plane

1. ## paralell to xy, yz, xz plane

I need some clarification on what being parallel to the xy, yz, and zx planes would mean when you are talking about parametric and symmetric equations.

2. ## Re: paralell to xy, yz, xz plane

Originally Posted by shmiks
I need some clarification on what being parallel to the xy, yz, and zx planes would mean when you are talking about parametric and symmetric equations.
The line $\ell(t):P+\vec{D}t$ is parallel to the $xy\text{-plane}$ provided $\vec{D}\cdot \vec{k}=0$.

The plane $(z-c)=0$ is parallel to the $xy\text{-plane}$.

There are similar statement for the other coordinate planes.