Ex 11.1, 12 - Chapter 11 Class 10 Areas related to Circles

Last updated at August 17, 2026 by

Ex 11.1, 12 - To warn ships for underwater rocks, a lighthouse - Ex 11.1

part 2 - Ex 11.1, 12 - Ex 11.1 - Serial order wise - Chapter 11 Class 10 Areas related to Circles

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Ex 11.1, 12 To warn ships for underwater rocks, a lighthouse spreads a red coloured light over a sector of angle 80° to a distance of 16.5 km. Find the area of the sea over which the ships are warned. (Use π= 3.14) Radius (r) = 16.5 km And, 𝜽=𝟖𝟎° Area over which ships are warned = Area of sector with angle 80° = 𝜃/(360°)×𝜋𝑟2 = (𝟖𝟎°)/𝟑𝟔𝟎×𝟐𝟐/𝟕 × (𝟏𝟔.𝟓)𝟐 = 80/360×22/7 × 16.5 × 16.5 = 2/9×22/7×165/10×165/10 = 189.97 km2 Hence, Area of sea cover = 189.97 km2

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