=[sin(x/2)cos(x/2)]^2 =[(1/2)*sin(x/2)cos(x/2)]^2 =(1/4)[sin(2*x/2)}^2 =(1/4)(sinx)^2
等于4分之1倍的（sinx的平方）
[sin^2(x/2)]*[cos^2(x/2)] 相关知识点: 试题来源: 解析 是不是[sin(x/2)]^2*[cos(x/2)]^2?如果是则[sin(x/2)]^2*[cos(x/2)]^2=[sin(x/2)cos(x/2)]^2=[(1/2)*sin(x/2)cos(x/2)]^2=(1/4)[sin(2*x/2)}^2=(1/4)(sinx)^2 ...
[sin^2(x/2)]*[cos^2(x/2)] 相关知识点: 试题来源: 解析 是不是[sin(x/2)]^2*[cos(x/2)]^2?如果是则[sin(x/2)]^2*[cos(x/2)]^2=[sin(x/2)cos(x/2)]^2=[(1/2)*sin(x/2)cos(x/2)]^2=(1/4)[sin(2*x/2)}^2=(1/4)(sinx)^2...
是不是[sin(x/2)]^2*[cos(x/2)]^2？ 如果是则 [sin(x/2)]^2*[cos(x/2)]^2 =[...
sin3a =sin(a+2a)=sin2a·cosa+cos2a·sina =2sina(1-sin²a)+(1-2sin²a)sina =3sina-4sin³a cos3a =cos(2a+a)=cos2acosa-sin2asina =(2cos²a-1)cosa-2(1-cos²a)cosa =4cos³a-3cosa sin3a cos3a 上述两式相比可得：tan3a 四倍角公式 sin4a=-4×[cosa·sina·(2×...