How many pairs of perpendicular lines are there in the square below?
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How many pairs of perpendicular lines are there in the square below?
Let's remember that perpendicular lines are lines that form a right angle of 90 degrees between them.
Our right angles are:
The lines that form angle ABC are: AB+BC
The lines that form angle BCD are: BC+CD
The lines that form angle CDA are: CD+DA
The lines that form angle DAB are: DA+AB
Since in a rectangle we have 4 marked angles of 90 degrees, we must have 4 pairs of perpendicular lines.
4
What do the four figures below have in common?
Each corner has exactly two lines meeting at 90°. For example, corner A has lines AB and AD - that's one pair of perpendicular lines, not two separate items.
Yes! By definition, a square has four right angles. Each corner shows two sides meeting perpendicularly, which is what creates those perfect 90° angles.
This happens when students count both AB ⊥ BC and BC ⊥ AB. Remember: order doesn't matter - these represent the same perpendicular relationship!
Look for the right angle symbols (small squares) at corners, or measure angles. If two lines meet at exactly 90°, they're perpendicular.
Great thinking! But this problem only shows the four sides of the square. Diagonals would create additional perpendicular relationships, but they're not drawn here.
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