projective straight line

例句：

1. 1. Theprojective line is the line that passes through a point and intersects another line at right angles.
   投影线是通过一点并与另一条直线成直角相交的线。
2. 2. The projective plane is a two-dimensional geometrical figure that can be used to draw lines in three dimensions.
   投影平面是一种二维几何图形，可以用来在三维空间中绘制线条。
3. 3. In mathematics, a projective transformation is a type of transformation that preserves the shape of objects but changes their position relative to each other.
   在数学中，一种投影变换是保持物体形状不变的变换，但改变它们相对于彼此的位置。