立體的點、線及平面 | Points, Lines and Planes in 3-D Figures

影片內容：

00:25 – 與平面垂直的線 | line perpendicular to a plane
01:06 – 點和線在平面上的投影 | projection of a point and a line onto a plane
03:06 – 線與平面的交角 | angle between a line and a plane
03:39 – 例子 1 | example 1
05:43 – 兩個平面的交線 | line of intersection between two planes
06:43 – 兩個平面的交角 | angle between two planes
08:08 – 例子 2 | example 2