When they meet each other at 90 degrees.
First of all, it is spelled perpindicular, not perpandiculer. Secondly, perpindicular lines are two lies that cross forming right angles, or 90 degree angles. For example, the two lines forming a plus sign are perpindicular.
If you are asking what are perpindicular lines, they are two lines that cross to form right angles, or 90 degree angles. An example of this is a plus sign (+). The two lines forming the plus sign are perpindicular to each other.
My guess as to what you are asking is what are the two different kinds of lines? If so, the two kinds of lines are parallel and perpindicular. Parallel is two lines that have the same slope, or in other words, could go on forever and not touch. An equals sign (=) is an example of this. If you drew lines on the two lines of the equals sign, and they were straight, they would, in theory, never touch. Perpindicular lines, however, is the opposite. It is two lines that form 90 degree angles or right angles. An example of this is a plus sign (+). The two lines that form the plus sign are perpindicular lines. My guess as to what you are asking is what are the two different kinds of lines? If so, the two kinds of lines are parallel and perpindicular. Parallel is two lines that have the same slope, or in other words, could go on forever and not touch. An equals sign (=) is an example of this. If you drew lines on the two lines of the equals sign, and they were straight, they would, in theory, never touch. Perpindicular lines, however, is the opposite. It is two lines that form 90 degree angles or right angles. An example of this is a plus sign (+). The two lines that form the plus sign are perpindicular lines.
no they don't have perpindicular lines
They are lines that intersect at 90 degrees
In two dimensional space they must. In three (or more) dimensions they need not.
lines and line segments
yes they can
none
no, a perpindicular is two lines with one interseption and where the lines meet they create 4 90 degree angles the lines create a t shepe.
They are lines that intersect one another at 90 degree angles.
Perpendicular lines are lines that intersect at a right angle (90 degrees).