f(0)=√2
∴2sin(2*0+Φ)=√2
∴Φ=π/4
f(-3π/4)=f(π-3π/4)/2=f(π/4)/2=2sin(π/2+π/4)/2=√2/2
f(2π)=2f(π)=4f(0)=4√2
当x属于[-π,0)时 f(x)=f(π+x)/2=sin(2π+2x+π/4)=sin(2x+π/4)
当x属于[0,π)时 f(x)=2sin(2x+π/4)
当x属于[π,2π)时 f(x)=f(π+x-π)=2f(x-π)=4sin(2x+π/4)
当x=2π时 f(x)=4√2
(3)f(x)=2sin(2x+π/4)
|f(x)-m|<4
-4
挺难算的,问题多
Φ=45度