***GeoGebra 教學 05 輸出動態圖檔***
https://www.youtube.com/watch?v=A2-_6IWNQC0
NCCU Moocs
https://www.youtube.com/watch?v=y2xIayKt9mA
馬鞍點_Saddle_point_無聲
Geogebra_3D_Saddle_point.mp4Geogebra_3D_Saddle_point.mp4