已知弦长L=6.83米，拱高H=60厘米=0.6米，求弧长C？弧半径为R，弧所对的圆心角为A。R=H/2+L^2/(8*H) =0.6/2+6.83^2/(8*0.6) =10.0185米A=2*ARC COS((R-H)/R) =2*ARC COS((10.0185-0.6)/10.0185) =39.86度C=π*R*A/180=π*10.0185*39.86/180=6.9697米
