Steps to creating 3 plane equations with 3 lines of intersection I was wondering if anyone can give me pointers on to how to mathematically create 3 plane equations that meet in 3 lines. In other words, each plane intersects one another in a straight line (so it sort of makes a triangle in a way)? 
Any help would be appreciated!

Hint: Suppose you take the case where all three lines point up, and then consider the normal vectors for the three planes. What do you notice? How would you represent this condition?
