cos(-20π/3)=
cos(-2/3)π=?
cos(π/32)*cos(π/16)*cos(π/8)=
已知cos(π/6-a)=根号3/3,求cos(5π/6+a)-cos²(π/3+a)
已知cos(x-π/6)=-根号三分之三 则cos(x)+cos(x-π/3)的值是
函数y=cos(x-π3
已知(sinα-cosα)/(sinα+cosα)=1/3,则cos^4(π/3+α)-cos^4(π/6-α)的值为
cos(-pi/3)=?
求证cos2π/7+cosπ/3=cosπ/7+cos3π/7
已知cosα=1/3,α属于(π,2π),则cosπ/2等于
已知功率信号f(t)=20cos(400πt)cos(2000πt)V
判断下列函数y=cos(x+π/3)cos(x-π/3)的奇偶性
已知cos(π/2-A)=根号2cos(3/2π+B)