Perpendicular Lines

Lines At Right Angles To Each Other

IF
Lines are perpendicular

THEN
m₁ × m₂ = - 1

EXAMPLE [1]
y = 2x + 5
y = -0.5x + 12
(2)(-0.5) = -1 => Lines are perpendicular

EXAMPLE [2]
y = 3x + 7
y = -0.25x + 15
(3)(-0.25) = -0.75 => Lines are not perpendicular