Ex 12.2, 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 𝜃=80° Area over which ships are warned = Area of sector with angle 80° = 𝜃/(360°)×𝜋𝑟2 = (80°)/360×𝜋 (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 is a graduate from Indian Institute of Technology, Kanpur. He has been teaching from the past 12 years. He provides courses for Maths and Science at Teachoo.

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