 Hello and welcome to the session. In this session we will discuss surface area. Surface area of a solid is the sum of the areas of its faces. First we have surface area of a cuboid is equal to 2 into lb plus bh plus hl where l is the length of the cuboid, b is the width of the cuboid and h is the height of the cuboid. Now the faces excluding the top and bottom make the lateral surface area of the cuboid. Now the lateral surface area of the cuboid is equal to 2 into h into l plus b. Consider this cuboid, this is the length, this is the width and this is the height of the cuboid. We take the length to be 5 centimeters, width that is b equal to 6 centimeters and the height equal to 4 centimeters. Now we have surface area is equal to 2 into lb plus bh plus hl and this is equal to 2 into 30 plus 24 plus 20 that is equal to 2 into 74 and this is equal to 148 centimeter square is the surface area of the given cuboid. Next we have surface area of cube is equal to 6l square where l is the each side of the cube. Now the lateral surface area of the cube is also the faces excluding the top and bottom of the cube and it is given by that is we have the lateral surface area of cube is equal to 4l square where again l is the length of each side of the cube. Consider this cube now suppose that each side of the cube l is equal to 5 centimeters then we have surface area of this cube is equal to 6l square that is 6 into 5 square equal to 6 into 25 and this is equal to 150 centimeter square. Next we have surface area of cylinder. We take the cylinder to be right circular cylinder now this is equal to 2 pi r into r plus h where we have r is the radius of the base of cylinder and h is the height of the cylinder. Now the lateral surface area that is the faces excluding the top and bottom of the cylinder is given by 2 pi r h. Consider this right circular cylinder this is the height of the cylinder h and this is the base radius or radius of the base r. Suppose that r is equal to 2 centimeters and h that is the height of the cylinder is 5 centimeters then we have surface area of the cylinder is equal to 2 pi r into r plus h that is equal to 2 into 22 upon 7 into 2 into 7. So this is equal to 88 centimeters square is the surface area of the cylinder. This completes this session hope you have understood how we find the surface area of cube void cube by cylinder.