把函数f(x)=sin(7π/8-x)*cos(x+π/8)的图象向右平移a(a>0)的单位,得函数g(x)图象,且g(

解 （1）f(x)=sin(7π/8-x)*cos(x+π/8)=sin[π-（π/8+x)]cos(x+π/8)
=sin(x+π/8)cos(x+π/8)=1/2sin(2x+π/4)
则g(x)=f(x-a)=1/2sin(2x-2a+π/4)
由于g(X)图象关于直线x=π/4对称
所以 2*π/4-2a+π/4=kπ+π/2 (k∈Z)
a=-kπ/2+π/8 (k∈Z)
则a的最小值为π/8
（2）f(x)=1/2sin(2x+π/4)
由于x∈[(2b+1)π/8,(3b+2)π/8](b∈N)时,过函数f(x)图象上任意两点的直线的斜率恒大于零
因此f(x)在∈[(2b+1)π/8,(3b+2)π/8](b∈N)为增函数
函数f(x)=1/2sin(2x+π/4)在[kπ-3π/8,kπ+π/8 ] (k∈Z)为增函数
则 (2b+1)π/8≥kπ-3π/8 且(3b+2)π/8≤kπ+π/8 (k∈Z)
又 b∈N 因此b=2