# Plane Equations

1. Dec 27, 2014

According to my book, if we write the equation of a plane as:

$ax + by + cz = d$

And two planes have values of $d$ with the same sign, they are on the same side of the origin. If they have values of $d$ with different signs, they are on opposite sides of the origin.

I'm confused as to whether this applies strictly to two parallel planes, or any pair of planes.

2. Dec 27, 2014

### jbriggs444

You must decide what "same side of the origin" means for non-parallel planes.

3. Dec 27, 2014