Ch 5 deepens understanding of lines and angles. Students learn about related angles (complementary, supplementary, adjacent, linear pairs, vertically opposite), and the properties of angles formed when a transversal intersects parallel lines.
Complementary angles sum to 90°. Supplementary angles sum to 180°. Adjacent angles share a common vertex and arm. A linear pair consists of two adjacent angles whose non-common arms form a straight line (sum = 180°). Vertically opposite angles are equal.
When a transversal cuts two parallel lines, it creates 8 angles with special relationships: corresponding angles are equal, alternate interior angles are equal, alternate exterior angles are equal, and co-interior (same-side interior) angles are supplementary.
Download: https://ncert.nic.in/textbook/pdf/gemh105.pdf | Complete book: https://ncert.nic.in/textbook/pdf/gemh1ps.zip
When two lines intersect, they form two pairs of opposite angles. Each pair consists of vertically opposite angles, and they are always equal.
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