弧长C=4730，弧高H=500，求半径R和弦长L？
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=5593
R1=5505.201
R2=5505.811
R3=5505.813
R4=5505.813
R=5505.813
A=C/R=4730/5505.813=0.8590920178弧度=0.8590920178*180/π=49.22度
L=2*R*SIN(A/2)
=2*5505.813*SIN(49.22/2)
=4585.881
