弧形弦长L=6M·弓高H=1.2M·求弧长C?弧半径为R,糊所对的圆心角为A.R^2=(R-H)^2+(L/2)^2R^2=R^2-2*R*H+H^2+L^2/42*R*H=H^2+L^2/4R=H/2+L^2/(8*H)=1.2/2+6^2/(8*1.2)=4.35MA=2*ARC SIN((L/2)/R)=2*ARC SIN((6/2)/4.35)...