Meaning & History. Possibly from the name of the Greek city of Delphi, the site of an oracle of Apollo, which is possibly related to Greek Î´ÎµÎ»ÏÏÏ (delphys) womb. It was used in the play 'The Prophetess' (1647), in which it belongs to the title prophetess. Popularity. See Popularity Detail.
In elementary geometry, the property of being perpendicular (perpendicularity) is the relationship between two lines which meet at a right angle (90 degrees). The property extends to other related geometric objects. A line is said to be perpendicular to another line if the two lines intersect at a right angle. Explicitly, a first line is perpendicular to a second line if (1) the two lines meet; and (2) at the point of intersection the straight angle on one side of the first line is cut by the second line into two congruent angles.
Sections: Slope-intercept form, Point-slope form, Parallel and perpendicular lines. There is one other consideration for straight-line equations: finding parallel and perpendicular lines. Here is the usual format for the question: 1  Given the line 2x â 3y = 9 and the point (4, â1), find lines through the point that are:his is the parallel line that they asked for. For the perpendicular line, I have to find the perpendicular slope. The reference slope is m = 2/3, and, for the perpendicular slope, I'll flip this slope and change the sign. Then the perpendicular slope is m = â 3/2.