Sin^4 23 п/12-cos^4 13 п/12

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3 марта, 06:25

Sin^4 23 п/12-cos^4 13 п/12

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Земфира · Answer 1

Sin⁴ (23π/12) - cos⁴ (23π/12) = (sin² (23π/12) + cos² (23π/12)) * (sin² (23π/12) - cos² (23π/12)) = 1 * (sin² (23π/12) - cos² (23π/12)) = - (cos² (23π/12) - sin² (23π/12)) = - cos (2 * (23π/12)) = - cos (23π/6) = - cos (24π/6-π/6) = - cos (4π-π/6) = - cos (π/6) = - 1/2