Geometry · Parallel Lines & Angle Pairs
Perpendicular Lines
HSG-CO.C.9
Definition
Two lines that intersect to form right angles.
Examples
- Perpendicular lines intersect at 90 degrees, forming four right angles, written a perpendicular to b.
- The x-axis and y-axis are perpendicular lines.
Key rule
Perpendicular lines always create four 90 degree angles at their intersection.
Memory hook
Crossing lines that make right angles.