Parallel lines

Parallel lines

1. Defination:- If two lines in a plane do not intersect each other, they are called parallel lines.

2. For example:- i) Railway Tracks , ii) opposite edges of text books , iii) Top of rectangular study table

3. 1. The distance between parallel lines dose not change, it is the same everywhere.

4. 3. Corresponding Angles

   • 1. If the two lines are parallel, then corresponding angles are equal. 2. If corresponding angles are equal, then the two lines are parallel.

5. 2. The lines, parallel to given line in a plane, are parallel to each other

6. 3. Two lines in the same plane perpendicular to a given line are parallel to each other.

7. 2. Alternate Angles

   • 2. Alternate Exterior Angles
     • •The exterior angles lie on the opposite sides of transversal and do not form a linear pair
   • 1. Alternate Interior Angles
     • • The interior angles lie on the opposite sides of a transversal and do not form a linear pair.

8. 1. Co- interior- angles

   • 1. If two lines are parallel, the sum of two co-interior angles is 180°. 2. If the sum of co- interior angles is 180°, then the two lines are parallel.

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