Angles and Lines

- The given figure represents ∠ABC with some points in its region.

- The region of the angle shaded by green colour lies between the two arms of the angle. This region is called the
**interior region of the angle**. Every point in this region is said to lie in the**interior**of the angle. Here, point P is in the interior.

- The region of the angle shaded by pink colour lies outside the two arms of the angle.This region is called the
**exterior region of the angle**. Every point in this region is said to lie in the**exterior**of the angle. Here, point Q and S are in the exterior.

- The boundary of ∠ABC is formed by its arms and . Every point lying on the arms is said to lie on the
**boundary of****the angle**. Here, points A, B, C and R lie on the boundary of the angle.

**Angle:**An angle is made up of two rays starting from a common end point.

In this figure, rays and have one common end point, that is, B. The rays and are called the arms or sides of the angle. The common end point B is the vertex of the angle.

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