1. Parallel and Perpendicular Lines

2. Parallel Lines
Parallel lines are two straight lines that never, ever meet.
Parallel lines are always the same distance apart.

3. Take a look at a stop sign.
A stop sign is an octagon. There are eight sides to an octagon. There are also four sets of parallel lines. Can you guess which lines are parallel to each other?

4. Parallel Lines In A Stop Sign
The four sets of parallel lines have been highlighted in different colors on this stop sign. Did you guess right?

5. What about this shape?
Here is a quadrilateral. How many sets of parallel lines are there here?

6. This figure has one set of parallel lines
This figure has one set of parallel lines. These are shown in the red, solid lines above. The dotted black lines are not parallel. They eventually will cross. They do not remain the same distance apart.

7. Perpendicular Lines
Perpendicular lines are lines that intersect, or pass through the same point.
Perpendicular lines intersect to form square corners, or 90° angles.

8. These two lines are perpendicular. The lines make a right angle
These two lines are perpendicular. The lines make a right angle. These two lines are not perpendicular. Why? The lines do not make a right angle where they meet.

9. How many sets of perpendicular lines are there in this sign
How many sets of perpendicular lines are there in this sign? Remember that perpendicular lines form 90° angles where they meet.

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