If two planes cross one another, then their intersection is two lines?

Question

michele_laino · Answer

I think that intersection between two planes can be a line, if the two planes are distinct, or a plane, if the two plane are coincident, namely the same plane.

directrix · Answer

Look at your postulates.

What is stated about when two DISTINCT planes intersect? The postulate will tell you how they intersect.

directrix · Answer

Look at postulate 6 in this list: http://www.cliffsnotes.com/math/geometry/fundamental-ideas/postulates-and-theorems

michele_laino · Answer

@Directrix  I named distinct planes those planes which are not the same plane and are not parallel each other, if the two planes are distinct and parallel there is no intersection. That is evident if we consider a plane in R^3, as described by an equation like this:
ax+by+cz=d
a secon plane distinct from the above plane can be described by this equation:
hx+ky+mz=n
where the coefficient a, b, c and h, k, m are not simultaneously equals.

directrix · Answer

I think that the OP is just beginning to study elementary Geometry which is why I suggested he study the beginning postulates. If the OP reads the postulates, he will get the answer about the two lines - get that it is incorrect.