intersection of 2 planes

[fairweather4me]

Have created 2 planes from a 3D model. How does one define/get coordinates for the intersection or line defining the intersection?
plane 1 (1',0,3'),(1',0,0),(-2,0,0),(-2,0,3')
plane 2

[fairweather4me]

I hit the wrong key, did not give plane 2:
plane 2 (1',-2',0),(1',0,0),(0,0,0),(0,-2',0)
How to find line common to both planes?

Would appreciate any approach, commands to use.
Thanks in advance,

David