Ex 8.4, 3 - Evaluate (i) sin2 63 + sin2 27 / cos2 17 + cos2 73

  1. Chapter 8 Class 10 Introduction to Trignometry
  2. Serial order wise
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Ex 8.4, 3 Evaluate : ( sin2 63 + sin2 27 )/(cos2 17 + cos2 73 ) ( sin2 63 + sin2 27 )/(cos2 17 + cos2 73 ) = (sin2 (90 27) + sin2 27 )/(cos2 (90 73) + cos2 73 ) = (cos^2 (27 ) + sin2 27 )/(sin^2 (73 ) + cos^2 73 ) = 1/1 = 1 Hence, ( sin2 65 + sin2 27 )/(sin2 17 + sin2 73 ) = 1 Ex 8.4, 3 Evaluate : sin 25 cos 65 + cos 25 sin 65 sin 25 cos 65 + cos 25 sin 65 = sin (90 65) cos 65 + cos (90 65) sin 65 = cos 65 cos 65 + sin 65 sin 65 = cos265 + sin265 = 1 Hence, sin65 cos 65 + cos 25 sin 65 = 1

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