答：
弦长AB=1500,弦高CD=380
则半弦长AD=BD=750
设圆半径R,根据勾股定理有：
R^2=AD^2+(R-CD)^2
R^2=AD^2+R^2-2CD*R+CD^2
R=(AD^2+CD^2)/(2CD)
=(AD^2)/(2CD)+CD/2
=750*750/(2*380)+380/2
=930.1315
圆心角2a,则sina=AD/R=750/930.1315=0.8063375
a=0.9379335弧度
所以：弧长=2aR=2*0.9379335*930.1315=1744.8
所以：弧长为1744.8