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Ex 13.4, 9 - A right circular cylinder just encloses a sphere - Area Of Sphere

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Ex 13.4, 9 - Chapter 13 Class 9 Surface Areas and Volumes - Part 2

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Ex 13.4, 9 - Chapter 13 Class 9 Surface Areas and Volumes - Part 3

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Ex 13.4, 9 Assume π = 22/7, unless stated otherwise. A right circular cylinder just encloses a sphere of radius r . Find surface area of the sphere, Radius of sphere = r Surface Area of sphere = 4πr2 Ex 13.4, 9 Assume π = 22/7, unless stated otherwise. A right circular cylinder just encloses a sphere of radius r . Find (ii) curved surface area of the cylinder, Curved Surface area of cylinder = 2𝜋rh Radius of cylinder = r It can be seen that Height of cylinder is twice the radius Height of cylinder (h)= r + r = 2r Curved Surface area of cylinder = 2𝜋rh = 2𝜋r(2r) = 4𝜋r2 Ex 13.4, 9 Assume π = 22/7, unless stated otherwise. A right circular cylinder just encloses a sphere of radius r . Find (iii) ratio of the areas obtained in (i) and (ii). Ratio = (𝑆𝑢𝑟𝑓𝑎𝑐𝑒 𝐴𝑟𝑒𝑎 𝑜𝑓 𝑠𝑝ℎ𝑒𝑟𝑒 𝑜𝑏𝑡𝑎𝑖𝑛𝑒𝑑 𝑖𝑛 (𝑖))/(𝑆𝑢𝑟𝑓𝑎𝑐𝑒 𝐴𝑟𝑒𝑎 𝑜𝑓 𝑐𝑦𝑙𝑖𝑛𝑑𝑒𝑟 𝑜𝑏𝑡𝑎𝑖𝑛𝑒𝑑 𝑖𝑛 (𝑖𝑖)) = (4𝜋𝑟^2)/(4𝜋𝑟^2 ) = 1/1 So the ratio is 1 : 1

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Davneet Singh

Davneet Singh has done his B.Tech from Indian Institute of Technology, Kanpur. He has been teaching from the past 12 years. He provides courses for Maths, Science, Social Science, Physics, Chemistry, Computer Science at Teachoo.