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.

• 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.

Written by Satish

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