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Ex 13.3, 3 - Curved surface area of a cone is 308 cm2 - Area Of Cone

  1. Chapter 13 Class 9 Surface Areas and Volumes
  2. Serial order wise
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Ex 13.3, 3 Curved surface area of a cone is 308 cm2 and its slant height is 14 cm. Find radius of the base and [𝐴𝑠𝑠𝑢𝑚𝑒 𝜋=22/7] It is given that Curved Surface Area of cone =308 πrl = 308 22/7×𝑟×14= 308 22×𝑟×2= 308 r = (308/(2 × 22)) cm ∴ r = 7 cm Therefore, the radius of the circular end of the cone is 7 cm. Ex 13.3, 3 Curved surface area of a cone is 308 cm2 and its slant height is 14 cm. Find (ii) total surface area of the cone. [𝐴𝑠𝑠𝑢𝑚𝑒 𝜋=22/7] We know that l = 14 cm, r = 7 cm Total surface area of cone = πr(l + r) = 22/7× 7× (14 + 7) = 22/7× 7 × 21 = 22 × 1 × 21 = 462 cm2 Therefore, the total surface area of the cone is 462 cm2.

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Davneet Singh
Davneet Singh is a graduate from Indian Institute of Technology, Kanpur. He provides courses for Mathematics from Class 9 to 12. You can ask questions here.
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