已知弧形的弦长L.拱高H如何求弧长C.半径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)A=2*ARC SIN((L/2)/R)度=2*(ARC SIN((L/2)/R))*PI/180弧度C=A*R...