are my legs. ( )
A:These
B:This
C:That
已知fx=2asin2x+π6+2a+b,x∈π4,3π4,是否存在常数a,b∈Q,使得f(x)的值域为y|-3≤y≤3-1?若存在,求出a,b的值;若不存在,说明理由.