Concise Selina Solutions for Class 10 maths Chapter 20 Cylinder, Cone and Sphere (Surface Area and Volume)


Poster tube and solar tank both these objects are in the shape of a cylinder. Some other objects like Tent, Joker's cap, funnel etc. are in the shape of a cone. In this topic, we shall learn as to how to find the area and capacity of cylindrical and conical objects. Surface Area of Cylinders. To find the surface area of a cylinder, add the surface area of each end plus the surface area of the side. Each end is a circle, so the surface area of each end is pi * r2, where r is the radius of the end. There are two ends, so their combined surface area is 2 pi * r2. Surface area to volume ratio can be found easily for several simple shapes, like for example, a cube or a sphere. The volume of a sphere is V= 4*Pi*R*R*R/3. So for a sphere, the ratio of surface area to volume is given by S/V = 3/R. A cone is a three-dimensional geometric shape that tapers smoothly from a flat base to a point called the apex or vertex. A cone is a solid that has a circular base and a single vertex. If the vertex is over the centre of the base, it is called a right cone. If it is not, it is called an oblique cone. An object that is shaped like a cone is said to be 'conical'.