Segments and their Measures:

Segments

A line segment is a part of a line that has two endpoints. The two endpoints of the line segment are used to name the line segment. A line has no endpoints, therefore it cannot be measured. But a line segment has two endpoints and hence the length can be measured.

Types of line segments

There are so many types of segments according to their properties. Some line segments will meet at a point. So they are called intersecting line segments.

When three or more lines meet at the same point, they are called concurrent line segments. When two line segments intersect to form a right angle, it is called perpendicular line segment.

Two line segments which do not intersect but are on the same plane are called parallel line segments.

Two line segments which cannot intersect as they are on the different planes are called skew line segment.

Two line segments which are of the same length are called congruent line segments. How to measure a line segment

The geometrical term line segment is used to denote all straight lines. Line segments are essentially a section of a line. A line is composed of an infinite series of points, each one represented by whatever symbol you choose, often represented by letters of the alphabet. The measurement of any line is infinite, but you can measure a segment of a line by finding two points, labeling them and calculating the distance between them with a straight edged ruler that uses inches and centimeters as units of measurement.

The measure of a line segment is the length of the line segment. Length of a line segment is indicated by segment name without the line above it.

If two line segments are congruent, then they have the same length.

We know even the usual non-Euclidean geometry accepts the definition of a line as the shortest distance between two points. It is also true that there are an infinite number of points in a line segment, but that's a consequence of treating distance as measurable by real numbers, rather than quantized.

The length of a line segment is the shortest distance between two points. But a distance is a number and neither a line nor a line segment is a number.

• Distance ratios may be real or rational numbers, but not any one distance value by itself; therefore they're usually represented as a number and a unit or nit distance.
• As far as it makes a difference: treating distance ratios as measureable by rational numbers can have the consequence of an infinite number of points in a line segment, too.
• It's plainly a matter of definition; if for any two distinct elements und corresponding distance values there were for whatever reason not yet another element and distance value between, then -- that's not a "line" in this sense. It, i.e. such a set of elements, might be called line.

In general, the straightness of any curve (and therefore, whether or not it constitutes a line) can be defined and evaluated from the distances measured between its elements, by Heron's formula.