# Straight line graphs

## Length of a line

A line segment is a section of the straight line that connects two points. Unlike a line, it does not extend in both directions of infinity.  To calculate the length, use the distance formula between the two points.

## Equation of a line through points

A straight line is an infinite one-dimensional shape and does not contain any amplitude. A straight line can be a combination of endless points connected to each side to some extent. A straight line doesn't have any curve in it.

## ax + by + c = 0

A straight line is represented by an equation of the form $$Ax+By+C=0$$.  In this case $$A$$, $$B$$ and $$C$$ are arbitrary constants. $$A$$ and $$B$$ cannot both be $$0$$ and $$x$$ and $$y$$ are variables. Divide the equation by $$B$$ and rearranging the terms yield,$$y=\frac{-A}{B}x+\frac{-C}{B}$$ Substitute $$\frac{-A}{B}=m$$ and $$\frac{-C}{B}=c$$ to get $$y=mx+c$$

## y = mx + c

Linear equations are equations that are of the first order. Linear equations are straight-line equations that have simple variable expressions with terms and without exponents. If we come across an equation with $$x$$ or $$y$$, it means we deal with a straight-line equation. If the slope of a line and $$y$$-intercept are given, we use the slope-intercept formula to find the equation of the line.

## Gradient of a straight line

The gradient is the measure of the angle of a point of a straight line. A gradient can go upward, which means from left to right, or downward, which means from right to left. The gradient can be positive as well as negative, and it does not need to be a whole number.

## Co-ordinates and scale

The coordinates of two numbers or the Cartesian co-ordinates are located at a specific point on a grid known as the coordinate plane. The co-ordinates can be two numbers, or a number and a letter.

## Co-ordinates and scales

The coordinates of two numbers or the Cartesian co-ordinates are located at a specific point on a grid known as the coordinate plane. The co-ordinates can be two numbers, or a number and a letter.