知道弦长9.
问题描述：
知道弦长9.
答
知道弦长L=9.6弦高H=3求弧长C?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) =3/2+9.6^2/(8*3)=5.34A=2*ARC SIN((L/2)/R)=2*ARC SIN((9.6/2)/5.34)=128.0...