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Learn in your speed, with individual attention - Teachoo Maths 1-on-1 Class


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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Davneet Singh

Davneet Singh has done his B.Tech from Indian Institute of Technology, Kanpur. He has been teaching from the past 13 years. He provides courses for Maths, Science, Social Science, Physics, Chemistry, Computer Science at Teachoo.