The word “tangent” means “to touch”. The Latin word for the same is “tangere”. In general, we can say that the line that intersect the circle exactly at one point on its circumference and never enters the circle’s interior is a tangent. In this sub-topic, we will learn about the concept of tangent to a circle and various theorems related to tangents.

In geometry, a tangent is a line drawn from an external point and passes through a point on the circle.

Definition

(a) If a line intersects a circle at exactly one point, then the line is called a tangent line of the circle.
(b) The point at which the tangent intersects the circle is called the point of tangency (or point of contact)
(c) If a line intersects a circle at two points, then the line is called a secant line of the circle.

If a line intersects a circle at two points, then the line is called a secant line of the circle.