Check sibling questions

Example 8 - Chapter 11 Class 9 Surface Areas and Volumes

Last updated at May 29, 2023 by

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

Learn in your speed, with individual attention - Teachoo Maths 1-on-1 Class

Book a free demo

Transcript

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 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

Ask a doubt
Davneet Singh's photo - Co-founder, Teachoo

Made by

Davneet Singh

Davneet Singh has done his B.Tech from Indian Institute of Technology, Kanpur. He has been teaching from the past 13 years. He provides courses for Maths, Science, Social Science, Physics, Chemistry, Computer Science at Teachoo.