弦长L=2100弧高H=395 弧长C多少?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) =395/2+2100^2/(8*395) =1593.07A=2*ARC SIN((L/2)/R) =2*ARC SIN((2100/2...