Math Calculators

Perpendicular Line Calculator

Find the equation of a line that passes through a given point and is perpendicular to a line of known slope.

Slope of perpendicular line —

y-intercept (b) —

Equation —

About the Perpendicular Line Calculator

Perpendicular lines intersect at a right angle. Their slopes are negative reciprocals of each other — multiplying the two slopes together always gives −1.

Formula: Perpendicular slope = −1 ÷ m · b = y₁ − (perpendicular slope) × x₁

This relationship is used to construct right angles, altitudes of triangles, and normal lines in geometry and physics.