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  1. Chapter 13 Class 10 Surface Areas and Volumes
  2. Serial order wise
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Ex 13.5, 5 An oil funnel made of tin sheet consists of a 10 cm long cylindrical portion attached to a frustum of a cone. If the total height is 22 cm, diameter of the cylindrical portion is 8 cm and the diameter of the top of the funnel is 18 cm, find the area of the tin sheet required to make the funnel (see Fig. 13.25) Area of tin sheet = CSA of Cylinder + CSA of frustum of cone Cylinder Radius of cylinder = 8/2 = 4cm Height of cylinder = 10cm CSA = 2 = 2 (8/2) 10 = 2 (4) 10 = 80 ^2 Frustum of cone Height of frustum = 22cm 10cm = 12cm _1=18/2 = 9cm _2=8/2 = 4cm CSA = ( _1+ _2 ) Slant height, l = ( ^2+( _1 _2 )^2 ) l = ((22 10)^2+(18/2 8/2)^2 ) l = ((12)^2+(9 4)^2 ) = ((12)^2+(5)^2 ) = (144 +25) = 169 = 13cm Thus, CSA = ( _1+ _2 ) = 13 (18/2+8/2) = 13 (9 + 4) = 13 13 = 169 ^2 Area of tin sheet = 80 + 169 = 249 ^2 = 249 3.14 ^2 = 781.86 ^2

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Davneet Singh is a graduate from Indian Institute of Technology, Kanpur. He has been teaching from the past 8 years. He provides courses for Maths and Science at Teachoo. You can check his NCERT Solutions from Class 6 to 12.