cos(π/12)^4+sin(π/12)^4=
cos(π/12)^4+sin(π/12)^4=
4 sinπ/12 cosπ/12=
sinπ/24*cosπ/24*sinπ/12=—— 答案是这么写的:1/2(2sinπ/24*cosπ/24)cosπ
a为锐角 cos(a+π/6)=4/5 求sin(2a+π/12)
若x=π/12,则cos^4x-sin^4x=
cos*π/12—sin*π/12
计算cosπ/12*sinπ/12
求值:sin(π/12)+cos(π/12)
已知 sinα+2cos(5π/2+α)/cos(π-α)-sin(π/2-α)=-1/4 求(sinα+cosα)平方
已知sinαcosα=-12/25,且3π/4
已知 sin(θ+kπ)=-2cos (θ+kπ) 求 ⑴4sinθ-2cosθ/5cosθ+3sinθ; ⑵(1/4)
已知α∈(0,π/2),且2sinα-sinαcosα-3cosα=0.求[sin(α+π/4)]/[sin2α+cos