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  1. Chapter 3 Class 11 Trigonometric Functions
  2. Serial order wise

Transcript

Example 4 The minute hand of a watch is 1.5 cm long. How far does its tip move in 40 minutes? (Use ฯ€ = 3.14). We know that ๐‘™ = r ฮธ Here, r = minute hand of clock = 1.5 cm Finding Angle ๐œƒ Now we know that Minute hand make 1 revolution in 1 hour Hence we can say that, Minute hand completes 360ยฐ in one hour In ๐‘Ÿ = ๐‘™/๐œƒ , ฮธ is in radians So, Degree completed in 1 minute = 360/60 Degree completed in 40 minute = 360/60 ร— 40ยฐ = 240ยฐ Hence ฮธ = 240ยฐ = 240ยฐ ร— ๐œ‹/(180ยฐ) = 4๐œ‹/3 Now Putting values in formula ๐‘™ = r ฮธ (Radian measure = ๐œ‹/180 ร— Degree measure ) = 1.5 ร— 4๐œ‹/3 = 0.5 ร— 4๐œ‹ = 2๐œ‹ = 2 ร— 3.14 = 6.28 cm

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Davneet Singh
Davneet Singh is a graduate from Indian Institute of Technology, Kanpur. He has been teaching from the past 9 years. He provides courses for Maths and Science at Teachoo.