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Write the value of 2 (sin6 x + cos6 x) − 3 (sin4 x + cos4 x) + 1. |
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Answer» sin6x + cos6x = (sin2x)3 + (cos2x)3 =(sin2x + cos2x)(sin4x+cos4x - sin2xcos2x) = 1 (sin4x + cos4x – sin2xcos2x) Substituting above value in given equation ⇒ 2(sin4x + cos4x – sin2xcos2x) - 3(sin4 x + cos4 x) + 1 ⇒ 2sin4x + 2cos4x – 2sin2xcos2x – 3sin4x - 3cos4x + 1. ⇒ -sin4x - cos4x - 2sin2xcos2x + 1 ⇒ -[(sin2x)2 + (cos2x)2 - 2sin2xcos2x] + 1 ⇒ -[( sin2x + cos2x)2] + 1 ⇒ -1 + 1 ⇒ 0 |
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