 Hi and welcome to the session. Today we will discuss about perimeter of closed figures. Suppose we have a figure A, B, C, D, E and we need to find its perimeter. So first of all let us learn what is perimeter. Perimeter is the distance covered boundary forming a closed figure when we go round the figure once. This figure perimeter will be equal to A, B plus B, C plus C, D plus D, E plus E, A. Sites of the boundary of this figure. Now suppose we are given the measurements of these sides then its perimeter will be equal to 15 centimetres the length of the sides of this figure. Also as the unit of all the sides is centimetre so the unit of the perimeter will also be centimetres. Now let us learn to find out the perimeter fin rectangle. We have a rectangle A, B, C, D in which B, C and A, D are the lengths of the rectangle which are equal. So let us denote it by L and A, B and D, C are the lengths of the rectangle which are also equal. So we will denote them by B closed figure so its perimeter will be equal to A, B plus B, C plus C, D plus D, A that is B plus L plus B plus L which will be equal to 2 times L plus B. So perimeter of rectangle is equal to 2 times length plus we are given that the length of this rectangle is 3 centimetres and the width of the rectangle is 2 centimetres then its perimeter will be equal to 2 times length that is 3 centimetres plus width that is 2 centimetres. So it will be equal to 10 centimetres. Now let us see how to find out the perimeter of regular shapes and we need to know what are regular shapes or regular figures are called regular closed figures. For example, equilateral triangle, regular pentagon etc. Now let us see what is the perimeter of a square. So here we have a square A, B, C, D and we know that in a square all the sides are equal. So let us say that all the sides of this square are equal to A so its perimeter will be equal to A, B plus B, C plus C, D plus D, A that is A plus A plus A plus A which will be equal to 4 times A and this can also be written as 4 into side of a square. Thus perimeter of a square is equal to 4 into length of a side which is equal to A over here we are given that the side of a square is equal to 2 centimetres then its perimeter will be equal to 4 into side that is 2 centimetres. So this will be equal to 8 centimetres. We will find out the perimeter of equilateral triangle. So here we have equilateral triangle A, B, C and we know that all the sides of equilateral triangle are equal. So suppose that all the sides of this equilateral triangle are equal to A, B, C will be equal to A, B plus B, C plus C, A, A plus A which will be equal to 3 A the length of the side of equilateral triangle is equal to 3 centimetres then its perimeter will be equal to 3 into 3 centimetres that is carefully then square is a regular length of a side similarly is a regular closed figure with three sides and its perimeter is number of sides that is 3 into length of a side. So by this we can say that length of a consider a regular pentagon. So this will be equal to 25 centimetres. In this session we have learnt to find out perimeter of a rectangle perimeter of any regular closed figure. With this we finish this session hope you must have understood all the concepts.