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Sin8A+Cot8A=1-4Sin2A.Cos2A+2Sin4A.Cos4A |
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Answer» (sin2 A + cos2 A)2 = 12 sin4 A + 2sin2A cos2 A +cos4 A = 1 You need to isolate the sum sin4 A + cos4 A to the left side such that: sin4 A + cos4 A = 1 - 2sin2A cos2 A You need to raise to square both sides such that: (sin4 A + cos4 A) = (1 - 2sin2A cos2 A)2 sin8 A + 2sin4 Acos4 A + cos8 A = 1 - 4sin2A cos2 A + 4sin4 A cos4 A Moving to the right 2sin4 Acos4 A yields: sin8 A +cos8 A = 1 - 4sin2A cos2 A + 4sin4 A cos4 A - 2sin4 Acos4 A sin8 A + cos8 A = 1 - 4sin2A cos2 A + 2sin4 A cos4 A |
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