已知弧长13.3米,弦长11.5米,半径5.75米,求弧高?

已知弧长C=13.3米,弦长L=11.5米,求弧高H?
弧半径为R,弧所对的圆心角为A.
Rn+1=(1+(L-2*Rn*SIN(C/(2*Rn)))/(L-C*COS(C/(2*Rn))))*Rn
R0=7
R1=7.209
R2=7.225
R3=7.225
R=7.225
A=2*ARC SIN((L/2)/R)
=2*ARC SIN((11.5/2)/7.225)
=105.47度
H=R-R*COS(A/2)
=7.225-7.225*COS(105.47/2)
=2.85