 Hello and welcome to the session. In this session, we will discuss quadrilaterals. Basically, a quadrilateral is a figure formed by joining four points in an order. Like this figure, A, B, C, D is formed by joining the points A, B, C, D in an order. So this A, B, C, D is a quadrilateral. As you can see, a quadrilateral has four sides, four angles and four vertices. Then a quadrilateral has two diagonals, A, C and B, D. Now the sum of the angles of a quadrilateral is 360 degrees and this is the anglesome property of a quadrilateral. Like in this quadrilateral, A, B, C, D, angle A plus angle B plus angle C plus angle D is equal to 360 degrees. Now we shall discuss types of quadrilaterals. First we have trapezium. This is a quadrilateral in which we have one pair of opposite sides are parallel. Like this quadrilateral A, B, C, D is a trapezium in which one pair of opposite sides that is A, B and C, D are parallel to each other. Then next is parallelogram. This is a kind of quadrilateral in which both pairs of opposite sides are parallel. So this A, B, C, D is a parallelogram in which we have A, B is parallel to C, D. Then B, C is parallel to A, D. Next is rectangle. Now this rectangle is a parallelogram in which one of its angles is right angle. Consider this figure A, B, C, D in which we have A, B is parallel to C, D. B, C is parallel to A, D that is A, B, C, D is a parallelogram and we are given that angle A is the right angle that is it is 90 degrees. So we say that A, B, C, D is a rectangle. Then we have rhombus which is a parallelogram in which all sides are equal. This figure A, B, C, D is a parallelogram as we have A, B is parallel to C, D and B, C is parallel to A, D and in this all sides are equal so this is a rhombus. Then we have square. Now a square is a parallelogram in which all sides are equal and all angles are right angles. In this parallelogram A, B, C, D we have all angles as right angles that is 90 degrees and all sides are also equal so this A, B, C, D is a square. Then another kind of quadrilateral is a kite in which we have two pairs of adjacent sides are equal and this quadrilateral kite is not a parallelogram. This A, B, C, D is a quadrilateral in which we have A, B is equal to A, D and B, C is equal to C, D. That is two pairs of adjacent sides are equal hence this quadrilateral A, B, C, D is a kite. So from above we notice that a square rectangle and rhombus parallelograms then we have a square is a rectangle and also a rhombus and a parallelogram is a trapezium but we have a trapezium not a parallelogram since only one pair of opposite sides is parallel in a trapezium and in parallelogram we require both pairs to be parallel. We know that a square is a rectangle and also a rhombus but a rectangle or a rhombus is not a square. This completes the session. Hopefully you have understood what is a quadrilateral and different types of quadrilaterals.