** Definition of Internal Tangent of a Circle**

- A tangent that is common to two circles and intersects the segment joining the centers of the circles is called Common Internal Tangent.

**More about Internal Tangent of a Circle**

- A common tangent can either be a common external tangent or a common internal tangent.

**Examples of Internal Tangent of a Circle**

- In figure,
**AB**line is the common internal tangent of two circles.

- In figure,
**CD**line is the common internal tangent of two circles.

**Solved Example on Internal Tangent of a Circle**

Identify the common internal tangent line from the given figure.

Choices:

A. AB line

B. CD line

C. EF line

D. none of the above

Correct Answer: A

Solution:

Step 1:A tangent that is common to two circles and intersects the segment joining the centers of the circles is called Common Internal Tangent.

Step 2:In figure, line AB is the common tangent as it intersects the segments joining the centers of two circles.

Step 3:So, AB is the common internal tangent line.

**Related Terms for Internal Tangent of a Circle**

- Circle
- Common External Tangent
- Intersect
- Segment
- Tangent