# Line

Line is a straight object with negligible width and depth. Line is a way to represent an object in coordinate system. Lines are one dimensional object. It is the distance from one point to another, which is known as starting point and ending point of a line.

Line segment is defined as a part of line which contains infinite points from starting point to the ending point. Ending points can be and cannot be a part of the line. Line segment defines the relationship between lines that if the lines are parallel to each other, intersecting each other etc.
In geometry line can be defined by a linear equation that is:
y = mx + c.

This line is defined in two dimensional coordinate system. Now we can say that line is a set of infinite points which lie on it and these coordinate points satisfy the linear equation.

In this equation 'm' is the slope of the line, 'c' is called as y- intercept and 'x' and 'y' is the coordinate of line. Here the slope of line can be calculated by the difference of coordinates.

m = (y2 – y1) /(x2 – x1),

In three dimensional coordinate system a line will be defined by parametric equations like:

x = x0 + at,

y = y0 + bt,

z = z0 + ct,

Now in this equation x, y, z are representing function of independent variable’t’.
x0, y0 and z0 are initial values of line with respect to x, y and z coordinates and a, b, and c are slopes of line.

## Theorem (If Two Lines intersect, Then they Intersect in exactly One Point)

If two points are considered to be collinear, then there can be only one line that passes through them because the line has a straight geometry. For two or more lines to pass through two given points, they must be collinear. From one single point many lines can pass and we can consider this point to be there intersect...Read More

Math Topics