弓形已知 弦高是H=925 弦长L=2800 弧长C怎么求 弧的半径为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)=925/2+2800^2/(8*925)=1521.96A=2*ARC SIN((L/2)/R)=2*AR...