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

Last updated at April 16, 2024 by Teachoo

Transcript

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

Davneet Singh has done his B.Tech from Indian Institute of Technology, Kanpur. He has been teaching from the past 14 years. He provides courses for Maths, Science, Social Science, Physics, Chemistry, Computer Science at Teachoo.

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