No, horizontal planes run parallel to each other, so they do not intersect, but two vertical planes can intersect.
Imagine the pages of a books as several planes. When you stand the book up, they are all vertical, but they all intersect at the book spine.
parallel planes
They are mutually perpendicular. However, they need not intersect: if they are in different planes, they will not intersect.
Yes. If two planes are not coincident (the same plane) and are not parallel, then they intersect in one straight line.
The angle between two planes when the planes intersect at a point is the acute angle fixed by the normal vectors of the planes.
No. Two planes may be parallel and so may not intersect. Also, any line is the intersection of infinitely many planes, not just two.
Two planes intersect at a line
A line. When two planes intersect, their intersection is a line.
In geometry, two planes intersect in a line. The only time this is not true is if the two planes are parallel to each other.
No, two planes do not intersect in exactly one plane unless the planes are exactly overlapping, making one plane. In Euclidean Geometry two planes intersect in exactly one line.
parallel planes
Two distinct planes will intersect in one straight line.
They are mutually perpendicular. However, they need not intersect: if they are in different planes, they will not intersect.
Yes. If two planes are not coincident (the same plane) and are not parallel, then they intersect in one straight line.
The intersection of two planes is a line.
The angle between two planes when the planes intersect at a point is the acute angle fixed by the normal vectors of the planes.
Two planes that intersect are simply called a plane to plane intersection. When they intersect, the intersection point is simply called a line.
No.