# Ex 11.3, 10 - Chapter 11 Class 7 Perimeter and Area

Last updated at Dec. 12, 2018 by Teachoo

Last updated at Dec. 12, 2018 by Teachoo

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. (๐๐๐๐ ๐=22/7) Remaining Area = Area of larger circle โ 2 ร Area of smaller circle โ Area of rectangle Area of larger circle Radius of larger circle = R = 14 cm Area of larger circle = ๐R2 = 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 = ๐r2 = 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, โด Remaining Area = Area of larger circle โ 2 ร Area of smaller circle โ Area of rectangle = 616 โ 2 ร (77/2) โ 3 = 616 โ 77 โ 3 = 616 โ 80 = 536 cm2 โด 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 9 years. He provides courses for Maths and Science at Teachoo.