arccos[cos(-pai/4)]=怎么考虑

arccos[cos(-pai/4)]=怎么考虑 arccos[cos(-pai/3)] arccos(cosπ/4)=cos(arccosπ/4)对吗? cos[arccos(-pai)]有没有意义 有意义的话等於什麼 为什么cos^2( pai/8)-sin^2( pai/8) =cos(pai/4) cos【arccos(-2/3)】=? cos(pai/4+x)=3/5,17pai/12 cos(pai/4+x)=3/5,17pai/12 cos(a+pai/4)=3/5,pai/2 函数y=arccos(x-pai/4)的最大植是______ 高中三角函数化简求值问题Cos(pai/17)*cos(2pai/17)*cos(4pai/17)*cos(8pai/17)=?详细过程或解法 求值Cos pai/17 *cos 2pai/17*cos 4pai/17*cos 8pai/17 已知cosa=-3/5,a属于(pai/2,pai),则cos(pai/4-a)= f x =sin(pai*x/4-pai/6)-2(cos pai*x/8)^2+1 cos(pai/15)×cos(2pai/15)×cos(3pai/15)×cos(4pai/15)×cos(5pai/15)×cos(6pai/15)×cos(7pai/15)求值 cos(pai/15)×cos(2pai/15)×cos(3pai/15)×cos(4pai/15)×cos(5pai/15)×cos(6pai/15)×cos(7pai/15)求值 求X ,arcsin(x-1)=pai-arccos(-1/2) sin(pai-a)cos(-8pai-a)=60/169且a属于(pai/4,pai/2)求cosa,sina