弦长L=2.5米, 拱高H=0.2米, 请问弧长C是多少?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^2/42*R*H=H^2+L^2/4R=H/2+L^2/(8*H)=0.2/2+2.5^2/(8*0.2)=4.00625米A=2*ARC SIN((L/2)/R)=2...