Question 29

The radii of circular ends of a bucket of height 24 cm are 15 cm and 5 cm. Find the area of its curved surface.

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Transcript

Question 29 The radii of circular ends of a bucket of height 24 cm are 15 cm and 5 cm. Find the area of its curved surface. Here, the bucket is in the shape of a frustum Where h = height = 16 cm r1 = radius of upper end = 20 cm r2 = radius of lower end = 8 cm We need to find its Curved Surface Area Curved Surface Area of frustum = ๐œ‹(๐‘Ÿ1+๐‘Ÿ2)๐‘™ We need to find l We know that ๐‘™ = โˆš(โ„Ž2+(๐‘Ÿ1โˆ’๐‘Ÿ2)2) ๐‘™ = โˆš(242+(15โˆ’5)2) ๐‘™ = โˆš(242+102) ๐‘™ = โˆš(576+100) ๐‘™ = โˆš676 ๐‘™ = โˆš(ใ€–26ใ€—^2 ) ๐‘™ = 26 cm Now, Curved surface area of frustum = ๐œ‹(๐‘Ÿ1+๐‘Ÿ2)๐‘™ = ๐œ‹(15+5)ร—26 = 22/7ร—20ร—26 = (440 ร— 26)/7 = 11440/7 = 1634.28 cm2 โˆด Curved surface area of frustum = 1634.28 cm2

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Davneet Singh
Davneet Singh is a graduate from Indian Institute of Technology, Kanpur. He has been teaching from the past 9 years. He provides courses for Maths and Science at Teachoo.