y=根号（-2cos^2 x+3cosx-1）+log(36-x^2) 的定义域

-2cos^2 x+3cosx-1>=0
36-x^2>0

36-x^2>0
x^2<36
-6<x<6

-2cos^2 x+3cosx-1>=0
2cos^2 x-3cosx+1<=0
(2cosx-1)(cosx-1)<=0
1/2<=cosx<=1
所以2kπ-π/3<=x<=2kπ+π/3
在-6<x<6范围内
则-6<x<=-5π/3,-π/3<=x<=π/3,5π/3<=x<6

定义域(-6,-5π/3]和[-π/3π/3]和[5π/3,6)