admin百科知識 2022-02-13 18:30:02 已知α是第二象限的角,且cos(α-π2)=15,求(sin(π+α)cos(π-α)tan(-3π2-α))(tan(π2+α)cos(3π2+α))的值已知α是第二象限的角,且cos(α-π/2)=1/5,求(sin(π α)cos(π-α)tan(-3π/2-α))/(tan(π/2 α)cos(3π/2 α))的值網友廻答:匿名網友cos(a-π/2)=1/5sina=1/5α是第二象限的角cosa=-2√6/5(sin(π a)cos(π-a)tan(-3π/2-a))/(tan(π/2 a)cos(3π/2 a))=-sina(-cosa)tana/((-tana)sina)=-cosa=2√6/5 db標簽 生活常識_百科知識_各類知識大全»已知α是第二象限的角,且cos(α-π2)=15,求(sin(π+α)cos(π-α)tan(-3π2-α))(tan(π2+α)cos(3π2+α))的值
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