cos^2 (x/2-7/8π)-cos^2(x/2+7π/8)可化简为?

cos^2 (x/2-7/8π)-cos^2(x/2+7π/8)可化简为? 化简cos²(x/2-7π/8）-cos²（x/2+7π/8) cos^2 π/8+cos ^2 3π/8+ cos^2 5π/8+cos^2 7π/8=? cos(-x-2π) 和cos(π-x) 化简 cos(π/17)*cos(2π/17)*cos(4π/17)*cos(8π/17) 求函数y=cos^2(x/2-7π/8)-cos^2(x/2+7π/8)的最大值 化简cos 2x (cos(x))^-2导数 cos(x^2)dx cos x>-1/2 证明cos 2x cos x=1/2(cos x+cos 3x) 化简函数y=cos^2(x+7π/12)-cos^2(x+π/12), 求函数y=7-4sin(x)cos(x)+4cos^2(x)-4cos^4(x)值 化简根号下[(1-cos x)/(1+cos x)] + 根号下[(1+cos x)/(1-cos x)]其中x属于（π/2,π） 证明:函数f(x)=cos^2+cos^2(x+π/3)+cos^2(x-π/3)是常数函数 0.5-cos^2(π/8) 若函数f(x)=[2cos^3 x-sin^2 (x+π)-2cos (-x-π)+1]/[2+2cos^2(7π+x)+cos(-x)],（1）求证f(x)是偶函数若函数f(x)=[2cos^3 x-sin^2 (x+π)-2cos (-x-π)+1]/[2+2cos^2(7π+x)+cos(-x)],（1）求证f(x)是偶函数 （2）求f(π/3)的值 2cos x (sin x -cos x)+1