Geometry · Circles
Tangent (Circle)
HSG-C.A.2
Definition
A line that touches a circle at exactly one point, perpendicular to the radius at that point.
Examples
- A tangent line touches the circle at one point and never crosses into it.
- The radius drawn to the point of tangency is always perpendicular to the tangent line.
Key rule
A tangent line always meets the radius at a 90 degree angle at the point of contact.
Memory hook
Touches once, perpendicular to the radius there.