f(x)=2a(1-cos2x)/2+sin2x-a
=sin2x-acos2x
=√(a^2+1)sin(2x+z)
其中tanz=a
x=3π/8是最大值
则2*3π/8+z=2kπ+π/2
z=2kπ-π/4
a=tanz=tan(2kπ-π/4)=-1
f(x)=2a(1-cos2x)/2+sin2x-a
=sin2x-acos2x
=√(a^2+1)sin(2x+z)
其中tanz=a
x=3π/8是最大值
则2*3π/8+z=2kπ+π/2
z=2kπ-π/4
a=tanz=tan(2kπ-π/4)=-1