1. Chapter 6 Class 12 Application of Derivatives
  2. Serial order wise


Example 1 Find the rate of change of the area of a circle per second with respect to its radius r when r = 5 cm.We have to find rate of change of area of circle with respect to radius i.e. we need to find (๐’…(๐‘จ๐’“๐’†๐’‚ ๐’๐’‡ ๐’„๐’Š๐’“๐’„๐’๐’†))/(๐’… (๐’“๐’‚๐’…๐’Š๐’–๐’” ๐’๐’‡ ๐’„๐’Š๐’“๐’„๐’๐’†)) = ๐’…๐‘จ/๐’…๐’“ We know that Area of circle = ฯ€ r2 A = ฯ€r2 Finding ๐’…๐‘จ/๐’…๐’“ ๐‘‘๐ด/๐‘‘๐‘Ÿ = (๐‘‘(๐œ‹๐‘Ÿ2))/๐‘‘๐‘Ÿ = ฯ€ ((๐‘Ÿ2))/๐‘‘๐‘Ÿ = ฯ€ (2r) = 2ฯ€r For r = 5 cm ๐‘‘๐ด/๐‘‘๐‘Ÿ = 2ฯ€ (5) = 10ฯ€ cmx/s

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Davneet Singh
Davneet Singh is a graduate from Indian Institute of Technology, Kanpur. He has been teaching from the past 10 years. He provides courses for Maths and Science at Teachoo.