How many pairs of perpendicular lines are there in the diagram below?
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How many pairs of perpendicular lines are there in the diagram below?
Remember that perpendicular lines are lines that intersect at a right angle of 90 degrees.
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 CDE are: CD+DE
The lines that form angle DEF are: DE+EF
The lines that form angle EFG are: EF+FG
The lines that form angle FGH are: FG+GH
The lines that form angle GHI are: GH+HI
The lines that form angle HIJ are: HI+IJ
The lines that form angle IJK are: IJ+JK
The lines that form angle JKL are: JK+KL
The lines that form angle KLA are: KL+LA
The lines that form angle LAB are: LA+AB
Due to the fact that in the drawing we have 12 angles of 90 degrees marked, we must have 12 pairs of perpendicular lines.
12
What do the four figures below have in common?
Look for the small square symbols at intersections! These markers indicate 90-degree angles, which means the two lines forming that angle are perpendicular.
Each perpendicular pair consists of exactly 2 lines meeting at a right angle. Even though there are many line segments in the cross shape, only adjacent segments that meet at right angles form perpendicular pairs.
Yes! If line AB is perpendicular to line BC and line BC is perpendicular to line CD, that's two separate pairs: AB⟂BC and BC⟂CD.
The lines form a plus sign (+) pattern with equal-length segments extending in four directions. This creates 12 right angles where adjacent segments meet.
Go around the perimeter systematically! Start at point A and move clockwise: until you return to . You should find exactly 12 right angles.
Only count angles with the square marker symbol! In geometry problems, these markers are the definitive way to show which angles are exactly 90 degrees.
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