the intersection of 2 planes is in one line true or false?

Question

and one more two planes intersect in only one point? geometry
HELP!! true or false

Answer 1

true

Answer 2

The question is not clearly worded.

In three dimensions, two planes can be:
(i) parallel = in which case they do not intersect
(ii) coincident = they have all points in common
(iii) neither parallel or coincident - in this case they intersect in one line - this is the most common case

In four or more dimensions there is the possibility that two planes could intersect in only one point. The three possibilities in three dimensions are also possible in four.
___________

In three dimensions three planes can be:
(i) all parallel - no intersection
(ii) two parallel and one transverse - the transverse plane intersects each of the two parallel planes in a line. The two lines are parallel.
(iii) three planes viewed edge on form a triangle - they intersect pairwise but there is no intersection of all three. The three lines of intersection of each pair of planes are all parallel.
(iv) None of the above - in the remaining case they intersect in one point - this is the most common case