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Tangent Lines (P1)


Drag the green dots to see more examples of the definitions related to circles and their tangent lines.

A TANGENT LINE is a line in the plane of the circle that intersects the circle in exactly one point.

The POINT OF TANGENCY is the point where a circle and a tangent intersect.

A TANGENT-CHORD ANGLE is an angle formed by an intersecting tangent and chord has its vertex “on”; the circle.


A) What is a tangent line? B) What are two important parts of a tangent line and the circle it is tangent to?