admin百科知識 2022-02-12 23:03:19 已知0(2)設函數f(x)=cosx-sinx,試求f(a)的值已知0(2)設函數f(x)=cosx-sinx,試求f(a)的值網友廻答:匿名網友(1)cosB=cos(B-π/4 π/4)=cos(B-π/4)cos(π/4)-sin(B-π/4)sin(π/4)=【(√2)/2】*(1/3-2√2/3)=(√2-4)/6,sinB^2=1-cosB^2===>sinB=(√2 4)/6,sin2B=2sinBcosB=2*(√2-4)/6*(√2 4)/6=-7/9(2)同樣sina=sin(a B-B),自己試試看. db標簽 生活常識_百科知識_各類知識大全»已知0(2)設函數f(x)=cosx-sinx,試求f(a)的值
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