PARALLEL LINES

PARALLEL LINES

1. CO-INTERIOR ANGLES

   • If two lines are parallel then the sum of co-interior angles is 180 °
     • Conversely , if the sum of co-interior angles is 180° then the two lines are parallel.

2. ALTERNATE ANGLES

   • If two lines are parallel then the alternate angles are equal.
     • Conversely , if the alternate angles are equal then the two lines are parallel.

3. CORRESPONDING ANGLES

   • If two lines are parallel then the corresponding angles are equal.
     • Conversely , if the corresponding angles are equal then the two lines are parallel.

4. If two lines in a plane do not intersect each other , they are called parallel lines

5. Examples : Lines on a writing pad&roadways and tracks

6. The distance between parallel lines does not change , it is the same every where.

7. Lines , parallel to a given line in a plane , are parallel to each other

8. Two lines in the same plane perpendicular to given line are parallel to each other.