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Last updated at Dec. 8, 2016 by Teachoo

Transcript

Ex 13.1, 6 A medicine capsule is in the shape of a cylinder with two hemispheres stuck to each of its ends (see figure). The length of the entire capsule is 14 mm and the diameter of the capsule is 5 mm. Find its surface area. Total area of the capsule = Curved Surface area of cylinder + Curved Surface area of 2 hemispheres Curved Surface area of cylinder Diameter of cylinder = 5 mm Radius of cylinder = (๐ท๐๐๐๐๐ก๐๐ )/2 = 5/2 mm Here, Diameter of hemisphere = 5mm So, Radius of hemisphere = (๐ท๐๐๐๐๐ก๐๐ )/2 = 5/2 mm Now, Height of cylinder + 2 ร Radius of hemisphere = 14 mm Height of cylinder = 14 โ 2 ร Radius of hemisphere = 14 โ 2 ร 5/2 = 14 โ 5 = 9 mm Curved surface Area of cylinder = 2๐rh = 2ร22/7ร5/2ร9 = (22 ร 45)/7 = 990/7 mm2 Curved Surface area of hemisphere Radius of hemisphere = 5/2 mm Curved Surface Area of hemisphere = 2๐r2 = 2 ร22/7ร (5/2)^2 = 2 ร22/7ร(5 ร 5)/(2 ร 2) = (11 ร 5 ร 5)/7 = 275/7 mm2 Curved Surface area of 2 hemispheres = 2 ร area of hemisphere = 2 ร 275/7 = 550/7 mm2 Total area of the capsule = Curved Surface area of cylinder + Curved Surface area of 2 hemispheres = 990/7+550/7 = (990 + 550)/7 = 1540/7 = 220 mm2 Hence, Total surface area of capsule = 220 mm2

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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.