已知弧长和拱高!求弦长!最好能算出半径!求救!

已知弧长C1=769.3,C2=549.5和拱高R1-R2=235!求弦长A和B!算出半径R1和R2?
弧所对的圆心角为α.
R1-R2=235
α=C1/R1=C2/R2
R2=(C2/C1)*R1=(549.5/769.3)*R1
R1-R2=R1-(549.5/769.3)*R1=235
769.3*R1-549.5*R1=219.8*R1=235*769.3=180785.5
R1=180785.5/219.8=822.5
R2=(C2/C1)*R1=(549.5/769.3)*822.5=587.5
α=C1/R1=769.3/822.5=0.935319弧度=0.935319*180/PI=53.59度
A=2*R1*SIN(α/2)=2*822.5*SIN(53.59/2)=741.56
B=2*R2*SIN(α/2)=2*587.5*SIN(53.59/2)=529.69