A:1:2:3
B:3:2:1
C:2:1:3
D:不能确定
“大江东去,浪淘尽,千古风流人物。故垒西边,人道是,三国周郎赤壁。乱石穿空,惊涛拍岸,卷起千堆雪。江山如画,一时多少豪杰。”
请回答:
将矩形纸片ABCD按如图所示的方式折叠,得到菱形AECF.若AB=3,则BC的长为( )
There were some children ____ (play) football on the playground.
已知函数f(x)=3cos2x+2sinxcosx,x∈R.
(1)求函数f(x)的最小正周期;
(2)求函数f(x)在区间0,π4上的值域.