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  1. Chapter 11 Class 7 Perimeter and Area
  2. Serial order wise

Transcript

Ex 11.3, 10 From a circular card sheet of radius 14 cm, two circles of radius 3.5 cm and a rectangle of length 3 cm and breadth 1cm are removed. (as shown in the adjoining figure). Find the area of the remaining sheet. (๐‘‡๐‘Ž๐‘˜๐‘’ ๐œ‹=22/7) Remaining Area = Area of larger circle โˆ’ 2 ร— Area of smaller circle โˆ’ Area of rectangle Area of larger circle Radius of larger circle = R = 14 cm Area of larger circle = ๐œ‹R2 = 22/7 ร— (14)2 = 22/7 ร— 14 ร— 14 = 22/1 ร— 2 ร— 14 = 44 ร— 14 = 616 cm2 Area of smaller circle Radius of larger circle = r = 3.5 cm Area of smaller circle = ๐œ‹r2 = 22/7 ร— (3.5)2 = 22/7 ร— (35/10)^2 = 22/1 ร— (7/2)^2 = 22/7 ร— 7/2 ร— 7/2 = 11/7 ร— 7/1 ร— 7/2 = 22/7 ร— 1 ร— 7/2 = 77/2 = 38.5 cm2 Area of rectangle Length of rectangle = l = 3 cm Breadth of rectangle = b = 1 cm Area of rectangle = l ร— b = 3 ร— 1 = 3 cm2 Therefore, โˆด Remaining Area = Area of larger circle โˆ’ 2 ร— Area of smaller circle โˆ’ Area of rectangle = 616 โˆ’ 2 ร— (77/2) โˆ’ 3 = 616 โˆ’ 77 โˆ’ 3 = 616 โˆ’ 80 = 536 cm2 โˆด Required area is 536 cm2

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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.