已知扇形的弧长为C=601,弦长为L=390,求半径R?
Rn+1=(1+(L-2*Rn*SIN(C/(2*Rn)))/(L-C*COS(C/(2*Rn))))*Rn
R0=200
R1=194.8
R2=195.09
R3=195.09