Let be the plane which is parallel to and which passes through the intersection of the planes

Find a Cartesian equation for .

First, we find the intersection of the two planes. This is the set of points which simultaneously satisfy

From the first equation we have

Plugging this into the second equation we have

This then gives us . So the line is the set of points where is arbitrary. Thus,

The plane must then contain this line and be parallel to the vector . Since it is parallel to its normal must be perpendicular to , thus,

and we must have

Therefore,

This has the Cartesian equation