Example 4 - Minute hand of a watch is 1.5 cm long. How far - Finding Value of trignometric functions, given other functions

  1. Chapter 3 Class 11 Trigonometric Functions
  2. Serial order wise
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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 Hence, r = minute hand of clock = 1.5 cm Now we know that Minute hand make 1 revolution in 1 hour and Hence we can say that Minute hand complete 360o in one hour So degree complete in 1 minute = 360/60 So degree complete in 40 minute = 360/60 ร— 40o = 240o Hence ฮธ = 240o = 240o ร— ๐œ‹/(180ยฐ) = 4๐œ‹/3 Now Putting values in formula ๐‘™ = r ฮธ = 1.5 ร— 4๐œ‹/3 = 0.5 ร— 4๐œ‹ = 2๐œ‹ = 2 ร— 3.14 = 6.28 cm

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