A、y=Asin2x
B、y=Acosx
C、<img width="151" height="21" src="http://admintk.100xuexi.com/UpLoadImage/2013-05-07/940c7dbb-cda6-477d-8b1a-c3880a15a573.png" />
D、<img width="176" height="20" src="http://admintk.100xuexi.com/UpLoadImage/2013-05-07/c2d69c3c-e6c9-4cbd-9807-0ae03a70f676.png" />