Lines in space that are parallel to perpendicular lines.

Orthogonal lines do not necessarily intersect, but perpendicular lines, by definition, do intersect.

### Educational note

Although the concepts of perpendicularity and orthogonality are sometimes used interchangeably in secondary education, where the main focus is on plane figures, it may be important to point out the difference between the two concepts. For example, two vectors are said to be orthogonal if their scalar product is zero. In a figure, it may be noted that it is not necessary for the lines that support these vectors to intersect.