Perpendicular Lines

Definition: Perpendicular lines are lines that intersect at a 90 degree angle. On the coordinate plane, perpendicular lines have opposite, reciprocal slopes.


Example: Identify the pair of perpendicular lines:



We know perpendicular lines intersect at a 90 degree angle. Using this information we can identify which pair of lines is perpendicular.

Step 1: Compare the given pairs of lines.

Step 2: Since Pairs 1, 2 and 4 do not intersect at 90 degree angles, we can determine pair 3 to be the best answer.

Option 3 best fits represents our definition of perpendicular lines.

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