已知弦长L=1525和弧高H=390,求弧长C的公式?弧半径为R,弧所对的圆心角为A.R^2=(R-H)^2+(L/2)^2R^2=R^2-2*H*R+H^2+L^2/42*H*R=H^2+L^2/4R=H/2+L^2/(8*H)=390/2+1525^2/(8*390)=940.393A=2*ARC SIN((L/2)/R)=2*ARC SIN(...