Ch 3 explores quadrilaterals and their properties in depth. Students learn the angle sum property (360°), classify quadrilaterals, and study special properties of parallelograms, rectangles, rhombuses, squares, trapeziums, and kites.
The sum of interior angles of a quadrilateral is 360°. Quadrilaterals are classified into: trapezium (one pair of parallel sides), parallelogram (two pairs), kite (two pairs of adjacent equal sides), and irregular quadrilaterals.
A parallelogram has: opposite sides equal and parallel, opposite angles equal, consecutive angles supplementary, diagonals bisect each other. Special cases: rectangle (all angles 90°, diagonals equal), rhombus (all sides equal, diagonals perpendicular), square (all sides equal, all angles 90°).
Download: https://ncert.nic.in/textbook/pdf/hemh103.pdf | Complete book: https://ncert.nic.in/textbook/pdf/hemh1ps.zip
Both have all four sides equal. A square additionally has all angles equal to 90° and equal diagonals. A rhombus can have any angle measure and its diagonals are not necessarily equal.
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