Algebra 1 · Linear Functions

Perpendicular Lines

Algebra 1 · Linear Functions

Definition

Perpendicular lines are lines that meet at a right angle, with slopes that are negative reciprocals.

Examples

  • Slopes 2 and -1/2 make perpendicular lines.
  • Slopes 3 and -1/3 are perpendicular.

Key rule

Multiply the two slopes and you get -1.

Memory hook

Perpendicular = flip it and change the sign.