就是写出sing(x)=0和±1时x的值
而且取g(x)=0,π/2,π,3π/2,2π
sin(2x-π/4)
所以这里g(x)=2x-π/4
所以解得x=π/8,3π/8,5π/8,7π/8,9π/8
所以五点是
(π/8,1),(3π/8,√2+1),(5π/8,1),(7π/8,-√2+1),(9π/8,1)