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Angles and Parallel Lines
Chapter summary, hard words and model exam answers for ICSE Class 10 Hindi.
Free online summary and notes (ICSE Class 10 Hindi). Read it here, no PDF download needed.
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Mathematics · CBSE 10 · ICSE 10 · GCSE (AQA, Edexcel, OCR)
Summary
A straight line is half a full turn, so angles sitting on it total 180°. A full turn around a point is 360°. These two facts solve most angle problems.
Crossing lines make four angles. The pair facing each other is equal; each neighbour pair adds to 180°.
The crossing line is called a transversal. Because the lines are parallel, the same eight angles appear in two equal sets.
Spot the letter shape between the parallel lines. F and Z mean 'equal'; C means 'add to 180°'.
Hard words & meanings
| vertex | the point where two rays or lines meet to form an angle |
| transversal | a line that crosses two or more other lines |
| parallel | lines that stay the same distance apart and never meet |
| corresponding angles | angles in the same position at each crossing; equal when lines are parallel (F-shape) |
| alternate angles | angles on opposite sides of the transversal between the lines; equal when parallel (Z-shape) |
| co-interior angles | angles on the same side of the transversal between the lines; add to 180° (C-shape) |
| vertically opposite | angles facing each other where two lines cross; always equal |
| supplementary | two angles that add up to 180° |
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