Example 8 - Chapter 11 Class 9 Surface Areas and Volumes

Last updated at August 7, 2026 by

Example 8 - The height and slant height of a cone are 21 cm - Examples

part 2 - Example 8 - Examples - Serial order wise - Chapter 11 Class 9 Surface Areas and Volumes

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Example 8 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 šœ‹š‘Ÿ2ā„Ž 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 ā€“ 212 = r2 r2 = 282 ā€“ 212 r2 = (28 ā€“ 21) (28 + 21) r2 = (7) (49) r = āˆš("7(49)" ) r = āˆš("7(7)2" ) r = 7āˆš7cm So, Volume of the come = 1/3 šœ‹š‘Ÿ2ā„Ž = 1/3 Ɨ 22/7 Ɨ 7 āˆš7 Ɨ 7 āˆš7 Ɨ 21 cm3 = 22 Ɨ 7āˆš7 Ɨ 7 āˆš7 cm3 = 22 Ɨ 7 Ɨ 7 Ɨ(āˆš7)2 cm3 = 22 Ɨ 7 Ɨ 7 Ɨ 7 cm3 = 7546 cm3

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