已知弦长L=3.4米,弦中点到弧高能H=0.4米,求弧长C?弧半径为R,弧所对的圆心角为A.R^2=(R-H)^2+(L/2)^2=R^2-2*R*H+H^2+L^2/42*R*H=H^2+L^2/4R=H/2+L^2/(8*H)=0.4/2+3.4^2/(8*0.4)=3.8125米A=2*ARC SIN((L/2)/R)=2*ARC S...