A:4080
B:3360
C:1920
D:720
某同学用甲图所示的电路探究“通过导体的电流与电压、电阻的关系”,电源电压恒为3V.
如图,直线l1∥l2,点A在直线l1上,以点A为圆心,适当长为半径画弧,分别交直线l1、l2于B、C两点,连结AC、BC.若∠ABC=56°,则∠1的大小为( )
— He Shanghai. He will be back in three days.