A line that intersects a circle in two points is called a secant line.
A line that intersects a circle in exactly one point - that touches a circle without going into it's interior - is called a [i][b]tangent[/b][/i]. [br][br]The point of intersection is called the [i][b]point of tangency[/b][/i].
Point of Tangency
Información: Defining Secant and Tangent Lines (Slide 5)