Last updated at May 29, 2018 by Teachoo

Transcript

Ex 13.1,9 A wooden article was made by scooping out a hemisphere from each end of a solid cylinder, as shown in figure. If the height of the cylinder is 10 cm, and its base is of radius 3.5 cm, find the total surface area of the article. Total surface area of article = Curved surface area of cylinder + 2 × Curved surface area of hemisphere Curved surface area of cylinder Radius = r = 3.5 cm Height of the cylinder = h = 10 cm Curved surface area of cylinder = 2πrh = 2 ×22/7×3.5× 10 = 2 × 22/7×35 = 2 × 22 × 5 = 220 cm2 Surface area of hemisphere Radius of hemisphere = r = 3.5 cm Surface area of hemisphere = 2πr2 = 2×22/7×(3.5)^2 = 2×22/7×3.5×3.5 = 2×22×0.5×3.5 = 44 ×0.5×3.5 = 77 cm2 Surface area of 2 hemisphere = 2 ×"Surface area of hemisphere" = 2 ×77 = 154 cm2 Total surface area of article = Curved surface area of cylinder + 2 × Curved surface area of hemisphere = 220 + 154 = 374 cm2 Hence , Total surface area of article = 374 cm2

About the Author

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.