The simplest definition of a line is it is the straight distance between two points. In geometry, line is a long thin mark made by a pencil or pen that runs straight from one point to another. In case the two points are fixed, it is called a line segment. If there are no apparent ends and the line seems to be infinitely long then it is known just as a line. If the line has one fixed end and stretches infinitely at the other end, then it is called a ray. A line has no thickness and is strictly a two dimensional figure.

### What are Perpendicular Lines?

Perpendicular lines are a set of two lines that form a right angle or an angle of ninety degrees. Imagine a horizontal line, exactly flat, and no imagine a vertical line standing atop it. The horizontal and vertical lines would meet at a point and that would form two angles on either side. Both angles would be ninety degrees. These two lines are called perpendicular lines. These right angles are also known as perpendicular angles.

In case of perpendicular lines, one line could be finite and another could be infinite, one could be a ray and another could be a line segment and both could be lines with infinite lengths. The two perpendicular lines may meet at a particular point thus forming two right angles or the two lines may crisscross each other and continue on their path, thus forming four right angles. It is not necessary for perpendicular lines to be exactly horizontal and vertical as a pair. They can form any kind of shape or be tilted or angled in any way. Regardless of what kind of tilt they have, the resulting angles formed by the crisscrossing of the two perpendicular lines would also be ninety degrees.

### Perpendicular Lines and Geometric Figures

Perpendicular lines don’t form any geometric figure or shape as such but when several perpendicular lines are brought together in specific ways, they can form square, cube, rectangle and the right triangle. Regular polygons usually don’t have perpendicular lines but irregular polygons can always have perpendicular lines forming one or more right angles. It all depends on the exact shape of the polygon, the number of sides and the length of the sides. Those would influence the angle and hence the likelihood of perpendicular lines forming a part of the geometric structure.