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


Transcript

Example 4 The minute hand of a watch is 1.5 cm long. How far does its tip move in 40 minutes? (Use π = 3.14). We know that 𝑙 = r θ Here, r = minute hand of clock = 1.5 cm Finding Angle 𝜃 Now we know that Minute hand make 1 revolution in 1 hour Hence we can say that, Minute hand completes 360° in 1 hour So, Degree completed in 1 minute = 𝟑𝟔𝟎/𝟔𝟎° Degree completed in 40 minute = 360/60 × 40° = 240° Converting degree into radians θ = 240° = 240° × 𝝅/(𝟏𝟖𝟎°) = 𝟒𝝅/𝟑 Putting values in formula θ "= " 𝑙/𝑟 " " 𝒍 = r θ = 1.5 × 𝟒𝝅/𝟑 = 0.5 × 4𝜋 = 2𝝅 = 2 × 3.14 = 6.28 cm

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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.