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Example 5 - The height of a cone is 16 cm and its base - Examples

Example 5 - Chapter 13 Class 9 Surface Areas and Volumes - Part 2

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Example 5 The height of a cone is 16 cm and its base radius is 12 cm. Find the curved surface area and the total surface area of the cone (Use π = 3.14). Curved surface area of cone = πr l Here, h = 16 cm and r = 12 cm. Let slant height be l We know that l2 = h2 + r2 l2 = "(16)2 + (12)2" l2 = "256 + 144" l2 = 400 l = √("400" ) l = √("202" ) l = 20 cm Curved surface area of cone = πr l = 3.14 × 12 × 20 cm2 = 753.6 cm2 Total surface area of cone = πr(l + r) = 3.14 × 12 (20 + 12) cm2 = 3.14 × 12 (32) cm2 = 1205.76 cm2

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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.