 Hi and welcome to the session. Today we will learn about quadrilaterals. A quadrilateral is a polygon which has four sides. So in this session we will study about different types of quadrilaterals such as parallelogram, rectangle, square, rhombus and trapezium. So let us start with a parallelogram. In a parallelogram opposite sides are parallel and equal. So here in this parallelogram side AB is parallel to side DC, AD is parallel to BC. Also AB is equal to BC and AD is equal to BC. Now opposite angles of a parallelogram are equal. So here angle A is equal to angle C and angle B is equal to angle B. Now we have a rectangle. In a rectangle opposite sides parallel and equal. So here PQ is parallel to SR and PS is parallel to QR. Also PQ is equal to SR and PS is equal to QR. Now all the angles of a rectangle are right angles. That means all the angles of a rectangle are equal as well. Also the diagonals of a rectangle are equal. So that means diagonal PR is equal to diagonal SQ. So by the properties of rectangle we can say that a rectangle can be thought of as a special parallelogram. Now let us study the properties of a square. In a square sides parallel that is AB is parallel to DC and AD is parallel to BC. Now all the sides of a square are equal. So here AB is equal to BC is equal to CD is equal to DA. Now all the angles of a square are right angles. That means all the angles of a square are equal also. Lastly the diagonals of a square are equal and are perpendicular to each other. So here diagonal AC is equal to diagonal VD and these are perpendicular to each other. Let us study about rhombus. In a rhombus opposite sides are parallel. So here PS is parallel to QR and PQ is parallel to SR. Now sides of a rhombus are equal. So we have PQ is equal to QR is equal to RS is equal to SP. Also in a rhombus opposite angles are equal. So here angle P is equal to angle R and angle S is equal to angle Q. The diagonals of a rhombus are perpendicular to each other. That means PR and NSQ are perpendicular to each other. Lastly we have a trapezium. In a trapezium one pair of opposite sides is parallel. So here side AB is parallel to side DC. Now our next topic is polygons. We classified polygons according to the number of sides and we know that a polygon with three sides is a triangle like this and a polygon with four sides is a quadrilateral. Now a polygon with five sides is a pentagon. Now a polygon with six sides is a hexagon and a polygon with eight sides is an octagon. Thus in this session we have learnt about quadrilaterals and polygons. With this we finish this session. Hope you have understood all the concepts. Goodbye, take care and have a nice day.