已知弦长L=2.83,弧长C=4.23,求半径R?
Rn+1=(1+(L-2*Rn*SIN(C/(2*Rn)))/(L-C*COS(C/(2*Rn))))*Rn
R0=1.5
R1=1.409
R2=1.419
R3=1.42
R4=1.42
R=1.42