8.1 INTRODUCTION:
* A figure formed by joining four points in an order is called a quadrilateral.
* A quadrilateral has 4 sides, 4 angles and 4 vertices.
* A quadrilateral has 2 diagonals.
* The sum of the angles of a quadrilateral is 3600
* Trapezium, parallelogram, rectangle, rhombus, square etc are different types of quadrilaterals.