f(x)=a(2cos平方x/2+sinx)+b=a(cosx+sinx+1)+b=a根號2sin(x+π/4)+a+b
(1）當(dāng)a=1時,f(x)在【2kπ-3π/4,2kπ+π/4]k屬于z,上是增函數(shù),在【2kπ+π/4,2kπ+5π/4]k屬于z,是減函數(shù)
(2)當(dāng)x屬于［0,派］,f(x)值域［3,4］可知,a（根號2+1）+b=4,-a+b=3,解得a=1-二分之根號2