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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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