已知弦长L=5070拱高H=555求弧长C?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*R*H+H^2+L^2/4 2*R*H=H^2+L^2/4 R=H/2+L^2/(8*H)=555/2+5070^2/(8*555)=6066.89A=2*ARC SIN((L/2)/R)=2*ARC SIN((5070/2...C还比弦长小啊？同一r弧长增加200求拱高，感谢追加20朋友：对不起！是我打错了！已知弦长L=5070拱高H=555求弧长C?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*R*H+H^2+L^2/4 2*R*H=H^2+L^2/4 R=H/2+L^2/(8*H)=555/2+5070^2/(8*555)=6066.89A=2*ARC SIN((L/2)/R)=2*ARC SIN((5070/2)/6066.89)=49.4度C=PI*R*A/180=PI*6066.89*49.4/180=5230.49H=R-R*COS(A/2)=6066.89-6066.89*COS(49.4/2)=555同一r弧长增加200求拱高H?弧所对的圆心角为A。C=5230.49+200=5430.49A=C/R=5430.49/6066.89=0.895102弧度=0.895102*180/PI=51.286度H=R-R*COS(A/2)=6066.89-6066.89*COS(51.286/2)=597.53