知道弧高和弦长怎么算弧长?弧高190.弦长928,弧长是多少?

弧高H=190.弦长L=928,弧长C是多少?
弧半径为R,弧所对的圆心角为A.
R^2=(R-H)^2+(L/2)^2
R^2=R^2-2*H*R+H^2+L^2/4
2*H*R=H^2+L^2/4
R=H/2+L^2/(8*H)
=190/2+928^2/(8*190)
=661.568
A=2*ARC SIN((L/2)/R)
=2*ARC SIN((928/2)/661.568)
=89.073度
C=PI*R*A/180=PI*661.568*89.073/180=1028.486