已知弦长和弦高怎么计算弧长C?弦长L=118,弦高H=21.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)=21/2+118^2/(8*21)=93.381A=2*ARC SIN((L/2)/R)=2...