Revision Notes for Class 7 Maths Chapter 5: Parallel and Intersecting Lines

Quick revision notes summarizing all key concepts from Class 7 Maths Chapter 5 “Parallel and Intersecting Lines”. These Class 7 Mathematics Chapter 5 notes are ideal for quick revision just before exams.

Last Updated: September 23, 2026

• Two distinct straight lines can intersect at only one point; if they never meet, they are parallel.
• When two lines intersect, they form four angles. Vertically opposite angles (angles directly across from each other) are always equal.
• A linear pair consists of two adjacent angles on a straight line; they always sum to 180°.
• Perpendicular lines intersect at exactly 90°.
• A transversal is a line that crosses two or more other lines. When it crosses a pair of parallel lines, it creates several special angle pairs:
  • Corresponding angles (same relative position at each intersection) are equal.
  • Alternate interior angles (opposite sides of the transversal, between the two lines) are equal.
  • Co-interior angles (same side of the transversal, between the two lines) sum to 180°.
• Two lines that are both perpendicular to the same line are parallel to each other.
• Two lines that are each parallel to the same third line are parallel to each other.
• A line parallel to a given line l through an external point A can be constructed using a ruler and set-square, or via paper-folding (fold twice, each perpendicular to the previous crease).
• Optical illusions can make genuinely parallel lines appear curved or non-parallel due to surrounding slanted or radiating lines; always verify with a ruler or by checking constant perpendicular distance.

NCERT Solutions: Class 7 Maths Chapter 5
Extra Questions: Class 7 Maths Chapter 5

For the full chapter, see the Class 7 Maths book page and the Class 7 Maths Formulas Handbook.

Frequently Asked Questions

What is the difference between parallel lines and intersecting lines?
Parallel lines are lines in the same plane that never meet no matter how far extended, maintaining a constant distance apart, while intersecting lines cross each other at exactly one common point.

What happens to the angles formed when a transversal line crosses two parallel lines?
A transversal crossing two parallel lines creates pairs of equal corresponding angles and equal alternate angles, along with co-interior angles that add up to 180 degrees.

Written by Satish

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