It includes different types of lines and angles

2. If the sum of the measures of two angles is 90°, then they are called
complementary angles

3. If the sum of the measures of two angles is 180°,then they are called
supplementary.

4. Two angles having a common vertex and a common arm but
no common interior points are called adjacent angles .

5. Example ; scissor
When two lines intersect , the two pair of
angles formed without any common arm are
called vertically opposite angles .

6. If the non -common sides of a pair of adjacent
angles are in a straight line , then the angles
forms a linear pair .

7. A line which intersects a set of two or more
given lines at distinct points is called a
transversal .

8. The lines which cut each other at a
common point are called intersecting lines .