Parallel lines have the same slope, to find the parallel line at a given point you should simply calculate the slope, calculate the y intercept, and you’re pretty much done.

Finding the equation of the perpendicular line is somewhat similar, only calculating the slope is trickier. The slope of the perpendicular line is the negative reciprocal of the line slope, in other words, when multiplying the slopes of two perpendicular lines you should get -1.

Here’s how to find the equation of the line that is parallel to a given line and passes through a given point (click here):

In short, type in Parallel, the line and the point:

Click Go:

Here’s how to find the equation of the line that is perpendicular to a given line and passes through a given point (click here):

Type in Perpendicular, the line and the point:

Click Go:

Cheers,

Michal