弦长L=2.6米,弦到弧顶H=0.8米,求弧长C?弧半径为R,弧所对圆心角为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)=0.8/2+2.6^2/(8*0.8)=1.456米A=2*ARC SIN((L/2)/R)=2*ARC SIN((2.6/2)...