The intersection of two planes is a line.
always
sometimes
never

The answer is Somtimes

Step-by-step explanation:

When you have two planes whose intersection is not the empty set, you have two posibilites:

- The two planes are the same. In this case you don't have a line as the intersection of them, but it is again a plane.

-The two plane s are not the same .    Then the intersection must be a line by an incidence axiom.

{3 + i, 3 - i, 3, -1}

step-by-step explanation: