级数cos(π/3)+cos(π/9)+cos(π/27)+.判断收敛性
判断下列函数y=cos(x+π/3)cos(x-π/3)的奇偶性
y=cos(π/3-x)cos[π/2(x-1)]判断奇偶性
cos(π/32)*cos(π/16)*cos(π/8)=
cos^2(π/3-a)+cos^2(π/6+a)
cos(2π/3-α)能等于cosα?
COS多少等于π/3?
cos(-2/3)π=?
计算cos(a+5π/12)cos(a+π/6)+cos(π/12-a)cos(π/3-a)
化简cos平方α+cos平方(α-π/3)+cos平方(α+π/3) 急、~
【紧急求助】计算:cosα+cos(2π/3 +α)+cos(4π/3 +α)
cosθ^2+cos(θ+2π/3)^2+cos(θ-2π/3)^2 计算
求SINπ/64 COSπ/64 COSπ/32 COSπ/16 COSπ/8