底边L=2.26，高H=0.6，求弧长C?弧半径为R，弧所对的圆心角为A。R=H/2+L^2/(8*H)=0.6/2+2.26^2/(8*0.6)=1.3641A=2*ARC COS((R-H)/R)=2*ARC COS((1.3641-0.6)/1.0641)=111.868度C=π*R*A/180==π*111.868*1.3641/180=2.663
