Notes On Quadrilateral and Its Types - CBSE Class 9 Maths
A figure formed by joining four points in order is called a quadrilateral. A quadrilateral is a closed figure having four sides, four angles and four vertices and two diagonals. The sum of four angles of a quadrilateral is 360°. Quadrilaterals can be classified into different types based on the properties of their sides and angles. Trapezium A trapezium is a quadrilateral in which one pair of opposite sides is parallel. A trapezium with equal non-parallel sides and equal base angles is known as an isosceles trapezium.                                            Kite A kite is a quadrilateral in which two pairs of adjacent sides are equal in length and one pair of opposite angles, the ones that are between the sides of unequal length, are equal in measure and the diagonals intersect at right angles.   Parallelogram A parallelogram is a quadrilateral in which, opposite sides are parallel and equal. If each pair of opposite sides of a quadrilateral are equal, then it is a parallelogram. A quadrilateral is a parallelogram if a pair of opposite sides is equal and parallel. Opposite angles of a parallelogram are equal. If each pair of opposite angles of a quadrilateral are equal, then it is a parallelogram. Diagonals of a parallelogram bisect each other. If the diagonals of a quadrilateral bisect each other, then it is a parallelogram. A diagonal of a parallelogram divides it into two congruent triangles. In a parallelogram, the angles are not right angles. Rectangle A rectangle is a parallelogram in which, diagonals are equal and bisect each other. It is a parallelogram in whose one angle is a right angle. Square A square is a parallelogram in which, all the sides are equal, diagonals are equal and perpendicular bisectors of each other. A square is a rectangle with equal adjacent sides.  Rhombus A rhombus is a parallelogram in which, all the sides are equal and diagonals are perpendicular bisectors. A square is a rhombus in which, each angle measures 90°. Squares, rectangles and rhombuses are all examples of parallelograms.

#### Summary

A figure formed by joining four points in order is called a quadrilateral. A quadrilateral is a closed figure having four sides, four angles and four vertices and two diagonals. The sum of four angles of a quadrilateral is 360°. Quadrilaterals can be classified into different types based on the properties of their sides and angles. Trapezium A trapezium is a quadrilateral in which one pair of opposite sides is parallel. A trapezium with equal non-parallel sides and equal base angles is known as an isosceles trapezium.                                            Kite A kite is a quadrilateral in which two pairs of adjacent sides are equal in length and one pair of opposite angles, the ones that are between the sides of unequal length, are equal in measure and the diagonals intersect at right angles.   Parallelogram A parallelogram is a quadrilateral in which, opposite sides are parallel and equal. If each pair of opposite sides of a quadrilateral are equal, then it is a parallelogram. A quadrilateral is a parallelogram if a pair of opposite sides is equal and parallel. Opposite angles of a parallelogram are equal. If each pair of opposite angles of a quadrilateral are equal, then it is a parallelogram. Diagonals of a parallelogram bisect each other. If the diagonals of a quadrilateral bisect each other, then it is a parallelogram. A diagonal of a parallelogram divides it into two congruent triangles. In a parallelogram, the angles are not right angles. Rectangle A rectangle is a parallelogram in which, diagonals are equal and bisect each other. It is a parallelogram in whose one angle is a right angle. Square A square is a parallelogram in which, all the sides are equal, diagonals are equal and perpendicular bisectors of each other. A square is a rectangle with equal adjacent sides.  Rhombus A rhombus is a parallelogram in which, all the sides are equal and diagonals are perpendicular bisectors. A square is a rhombus in which, each angle measures 90°. Squares, rectangles and rhombuses are all examples of parallelograms.

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