admin百科知識 2022-02-12 23:03:37 sin a=13 則sin 3a=?sin a=1/3 則sin 3a=?網友廻答:匿名網友sin(3a)=sin(2a a)=sin(2a)cosa cos(2a)sina=2sinacosacosa [1-2(sina)^2]sina=2sina[1-(sina)^2] sina-2(sina)^3=2sina-2(sina)^3 sina-2(sina)^3=3sina-4(sina)^3=3(1/3)-4(1/3)^3=1-4/27=23/27 db標簽 生活常識_百科知識_各類知識大全»sin a=13 則sin 3a=?
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