# Straight Line

- A straight set of points that continue on to infinity in both directions. A straight line on the xy plane is defined by the equation:

- where
*m*= gradient*c*= intercept on y-axis

- When fitting a straight line to a set of experimental data the following may be applied to calculate the gradient (m) and y-axis intercept (c).

- For two straight lines defined as:
- and
- If
*m*_{1}=*m*_{2}the lines are parallel. - If
*m*_{1}**m*_{2}=-1 the two lines are perpendicular.

**See also: **Intercept, Line, Line of Best Fit, Linear, Linear Regression, Pearson Product Moment Correlation Coefficient, Slope, Slope of a Linear Function.

**Subjects: ** Mathematics