已知弦長L=5070拱高H=555求弧長C?弧半徑為R,弧所對的圓心角為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還比弦長小啊？同一r弧長增加200求拱高，感謝追加20朋友：對不起！是我打錯了！已知弦長L=5070拱高H=555求弧長C?弧半徑為R，弧所對的圓心角為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弧長增加200求拱高H?弧所對的圓心角為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