cos(1/2),

1-cosx等于 2sin05(x/2.
y(cos x-2(cos x-1)的值域
为三角内角 且2sin cos=1 求2sin-cos的值
(1/2)sin(π/12)cos(π/12(1/4)2sin(π 12)cos(π/12(1
y=2cos1/2x y=2cos(x-π/2 y=cos(1/2x π/4 这三个函数