1,ac(cosx/2+sinx/2,-sinx/2)
bc(cosx/2-sinx/2,2cosx/2)
2,f(x)=(cosx/2+sinx/2)*(cosx/2-sinx/2)-sinx
=cosx-sinx=根号2*cos(x+pi/4)
f(x)最小正周期是pi/2
3,x+pi/4∈[π/3,13π/12]
最大值是 2分之根号2
最小值是-根号2
1,ac(cosx/2+sinx/2,-sinx/2)
bc(cosx/2-sinx/2,2cosx/2)
2,f(x)=(cosx/2+sinx/2)*(cosx/2-sinx/2)-sinx
=cosx-sinx=根号2*cos(x+pi/4)
f(x)最小正周期是pi/2
3,x+pi/4∈[π/3,13π/12]
最大值是 2分之根号2
最小值是-根号2