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Example 15 - The height and slant height of a cone are 21 cm - Volume Of Cone

Example 15 - Chapter 13 Class 9 Surface Areas and Volumes - Part 2

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Example 15 The height and the slant height of a cone are 21 cm and 28 cm respectively. Find the volume of the cone. Volume of the come = 1/3 𝜋𝑟2ℎ Given slant height = l = 28 cm Height of cone = h = 21 cm Let radius of cone = r cm We know that l2 = h2 + r2 282 = 212 + r2 282 – 212 = r2 r2 = 282 – 212 r2 = (28 – 21) (28 + 21) r2 = (7) (49) r = √("7(49)" ) r = √("7(7)2" ) r = 7√7cm So, Volume of the come = 1/3 𝜋𝑟2ℎ = 1/3 × 22/7 × 7 √7 × 7 √7 × 21 cm3 = 22 × 7√7 × 7 √7 cm3 = 22 × 7 × 7 ×(√7)2 cm3 = 22 × 7 × 7 × 7 cm3 = 7546 cm3

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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.