若x∈(−3π4,π4)且cos(π4−x)=−35则cos2x的值是( )
若x∈(−3π4,π4)且cos(π4−x)=−35则cos2x的值是( )
已知cos(x−π2)=35,则cos2x的值为( )
(2012•湖北模拟)设函数f(x)=cos(2x−4π3)+2cos2x.
f(x)=cos²x·cos2x/1-cos²x(x∈0,π)的最小值是
已知sin x/2 -- 2cos x/2=0.(1)求tan x的值.(2)求 cos2x/(√2cos(π/4+x)
(2010•舟山模拟)已知函数f(x)=cos(2x−π3)+sin2x−cos2x.
已知tan(x-π/4),求(sin2x+2cos2x)/(2cos²x-3sin2x-1)的值
x∈(0,π/4)cos(π/4+x)=5/13 则cos2x=
(2014•湖北二模)已知函数f(x)=cos(2x−2π3)−cos2x(x∈R ).
(2011•渭南三模)设函数f(x)=cos(2x−π3)−cos2x,x∈R.
函数y=cos(π3−2x)−cos2x
已知函数f(x)=sin(2x+π6)−cos(2x+π3)+2cos2x.