2.下列函數(shù)中是偶函數(shù)的是( )
(A)y=sin2x (B)y=-sinx
(C)y=sin|x| (D)y=sinx+1
【解析】選C.所給選項(xiàng)中的四個(gè)函數(shù)定義域均為R,對(duì)C,由
f(-x)=sin|-x|=sin|x|=f(x),故是偶函數(shù).
3.(2008·天津高考)設(shè)函數(shù)f(x)=sin(2x- ),x∈R,則f(x)是( )
(A)最小正周期為π的奇函數(shù)
(B)最小正周期為π的偶函數(shù)