Adjacent and Linear Angles
Adjacent angles are two angles that share a common vertex and a common side. In other words, they are side by side and do not overlap. When two adjacent angles add up to 180 degrees, they are called linear angles.

Relation between Adjacent and Linear Angles
- Adjacent angles are always linear if they add up to 180 degrees.
- If two angles are adjacent and form a straight line, they are called a linear pair of angles.
- The sum of the measures of the angles in a linear pair is always 180 degrees.
- Linear pairs are always adjacent angles but not all adjacent angles are linear pairs.

NCERT Solution (Part - 2) - Triangle and Its Properties
In the context of triangles, adjacent and linear angles play a crucial role in understanding various properties and theorems. For instance:
- In a triangle, the angles opposite to two equal sides are equal.
- The exterior angle of a triangle is equal to the sum of the two interior opposite angles.
- The sum of all interior angles of a triangle is always 180 degrees.
- The exterior angle theorem states that the exterior angle of a triangle is greater than either of the two interior opposite angles.
Understanding the concepts of adjacent and linear angles is fundamental to solving problems related to triangles and their properties as per the NCERT syllabus.