已知弧长C=1800,弦长L=890,求弦高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=500
R1=467.725
R2=471.547
R3=471.613
R4=471.613
R=471.613
A=2*ARC SIN((L/2)/R)
=2*ARC SIN((890/2)/471.613)
=141.32度
H=R-R*COS(A/2)
=471.613-471.613*COS(141.32/2)
=315.428