# Parallel Lines

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The lines that do not intersect each other are called Parallel lines.
Example : Railway tracks,lines on the note book etc.

Transversal : The line which cuts the two parallel-lines in two distinct points is called transversal.

The eight angles are formed by parallel-lines and transversal , they are Types of Angles made by Transversal with two Lines
1) Corresponding angles : There are 4 pairs of corresponding angles. These angles are formed on letter
“F" .

If the lines are parallel then the measures of corresponding angles are equal.
 Corresponding Angles ∠a = ∠e ∠d = ∠h ∠b = ∠f ∠c = ∠g

2)Alternate interior angles : There are 2 pairs of alternate interior angles. These angles are formed on letter
“z" .

If the lines are parallel then the measures of alternate interior angles are equal.

 Alternate Interior Angles ∠d = ∠f ∠c = ∠e

3)Interior angles on the same side of transversal : There are two pairs of interior angles. These angles are formed on letter
“C" .

If the lines are parallel then the interior angles on the same side of transversal are supplementary.( sum up to 180)
 Interior Angles ∠a + ∠b = 1800 ∠c + ∠d = 1800

4) Alternate exterior angles : There are two pairs of alternate exterior angles. Alternate Exterior Angles ∠a = ∠g ∠b = ∠h

If the lines are parallel then the measures of alternate exterior angles are equal.
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Practice

Use the following figure and answer the given questions: 1) State all the corresponding angles.
2) Give the names of alternate interior angles.
3) If m∠b = 40
0 then find the remaining angles and state the reasons for it.
Basic Geometry

Point
Lines
Angles
Lines and Angles
Complementary angles
Supplementary angles
Vertically Opposite Angles
Linear Pair Angles