已知弦长L=12、弧高H=1.8,半径R=11.672,求圆心角A、面积S、弧长C?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)=1.8/2+12^2/(8*1.8)=10.9A=2*ARC SIN((L/2)/R)=2*ARC SIN((12/2)/10.9)...