已知弧长3000,拱高200,求弦长.(请将计算过程大致写一下) 或者有人会解 cos(1500/r)=(r-300)/

已知弧长C=3000,拱高H=200,求弦长L?
弧半径为R,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=6000
R1=5527.5
R2=5589.92
R3=5591.34
R4=5591.35
R5=5591.35
R=5591.35
A=C/R
=3000/5591.35
=0.53654弧度
=0.53654*180/PI
=30.742度
L=2*R*SIN(A/2)
=2*5591.35*SIN(30.742/2)
=2964.1