**Important Concepts and Formulas**

1.

**Secant:**A line which intersects the circle at two distinct points is called a secant of the circle.
2.

**Tangent:**A line which touches the circle at only one point is called a tangent. The tangent to a circle is a special case of the secant, when two end points of its corresponding chord coincide.
3.

**Theorem 1:**The tangent at any point of a circle is perpendicular to the radius through the point of contact.
4. The length of the segment of the tangent from the external
point P and the point of contact with the circle is called the length of the
tangent from the point P to the circle.

5.

**Theorem 2:**The lengths of tangents drawn from an external point to a circle are equal.
To study about the terms related to the circle ------- Click Here!