3. The builder uses the level to put the bricks horizontal (b). He uses the plummet to the wall is vertical (c), while the ladder is inclining (d).

   According to their position in the space, the lines can be horizontal, vertical and inclining.

   Answer these questions:   

   4. Parallel, perpendicular and oblique lines

   The lines a and b are parallel and although they extend, they will never get closer. 

   The Lines m (vertical) and n (horizontal) are perpendicular.

   The lines c and d, as well as e and f are not perpendicular, but oblique.
   
   Answer:

   5. The point and the line

   If we fold a piece of paper, we have a line that divides the plane into two semi-planes.

  6. The point

   We have a sheet of paper and we do two creases, the lines may intersect at a point. Endless lines can pass for a point. Only one line can pass for two points.

| Educational applications | Mathematics |
In Spanish  | Interactive

®Arturo Ramo García.-Record of intellectual property of Teruel (Spain) No 141, of 29-IX-1999
Plaza Playa de Aro, 3, 1º DO 44002-TERUEL