已知弦长L=750MM和弧长C=770MM,求半径R?
Rn+1=(1+(L-2*Rn*SIN(C/(2*Rn)))/(L-C*COS(C/(2*Rn))))*Rn
R0=1000
R1=969.25
R2=971.41
R3=971.43
R4=971.43
R=971.43MM