已知弧长C=1970,弧与对应弦的距离为H=300,求对应的弦长L?弧半径为R,弧所对的圆心角为A.Rn+1=(1-(Rn*COS(C/(2*Rn))-Rn+H)/((C/2)*SIN(C/(2*Rn))-H))*Rn R0=1500 R1=1559.5 R2=1564.28 R3=1564.32 R4=1564.32 R=1564.32 A=C/R=1970/1564.32=1.25933弧度=1.25933*180/PI=72.154度 L=2*R*SIN(A/2) =2*1564.32*SIN(72.154/2) =1842.38