Parallel lines are lines in the same plane that remain the same distance apart and do not meet, even when extended indefinitely; they may be horizontal, vertical, or slanted and need not be the same length. This understanding allows identification of parallel sides in shapes and distinguishes them from lines that merely appear not to intersect because only short segments are shown, without using angle relationships or formal geometric proofs.
Parallel lines are lines that:
They can be horizontal, vertical, or slanted. They do not have to be the same length.
Example: Look at rectangle .
A -------- B
| |
| |
D -------- C
Find the pairs of parallel sides.
Compare the top side with the bottom side .
They stay the same distance apart and will never meet.
So, is parallel to .
Compare the left side with the right side .
They also stay the same distance apart and will never meet.
So, is parallel to .
The pairs of parallel sides are:
and
To check any pair of lines, imagine extending both lines. If they stay the same distance apart and never meet, they are parallel.
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