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Sin^4A+2sin^A.cos^2=1-cos^4A |
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Answer» sin A+cos 4 A We have (a 2 +b 2 ) 2 =a 4 +b 4 +2A 2 b 2
⇒a 4 +b 4 =(a 2 +b 2 ) 2 −2a 2 b 2
Take a=sinA and b=cosA we get sin 4 A+cos 4 A=(sin 2 A+cos 2 A) 2 −2sin 2 2 A =1−2sin 2 Acos 2 A PROVED. |
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