Parallel Lines
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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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
• Adjacent Angles
• Parallel Lines
• Solved Problems on Intersecting Lines
• Solved Problems on Parallel Lines