弦长L=8米 拱高H=1米 求弧长C多少米?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)=1/2+8^2/(8*1)=8.5米A=2*ARC SIN((L/2)/R)=2*ARC SIN((8/2)/8.5)=56.1...