弦长L=6.3米拱高H=1.5米求弧长C是多少米？弧半径为R，弧所对的圆心角为A。R=H/2+L^2/(8*H)=1.5/2+6.3^2/(8*1.5)=4.0575米A=2*ARC COS((R-H)/R)=2*ARC COS((4.0575-1.5)/4.0575)=101.853度C=π*R*A/180=π*4.0575*101.853/180=7.2129米
