Geometry · Points, Lines & Angles
Right Angle
HSG-CO.A.1
Definition
An angle that measures exactly 90 degrees, shown with a small square mark.
Examples
- A right angle always measures exactly 90 degrees.
- The corner of a square or rectangle is a right angle.
Key rule
A right angle is always marked with a small corner square, not an arc.
Memory hook
Exactly 90 degrees — marked with a little square.