函数f(x)＝sinx＋sin(x＋π/2)
=sinx＋cosx
=√2[√2/2)sinx+(√2/2)cosx]
=√2sin(x+π/4)
x属于R,当sin(x+π/4)=1时最大,
所以√2sin(x+π/4)最大值为√2
即：
函数f(x)＝sinx＋sin(x＋π/2)最大值为√2