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perpendicular

Crossing at a perfect right (90°) angle.

Two lines are perpendicular when they cross at a 90° angle. In slope-intercept form, two non-vertical lines are perpendicular exactly when their slopes are negative reciprocals of each other, m_1 \cdot m_2 = -1.

Examples

  • A line with slope 2 is perpendicular to any line with slope -\frac12.

See also

parallel lines
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