Using a Ruler and Drafting Triangle

Constructing Parallel Lines

So, you want to draw a parallel line that has to pass through a point?

Easy to do using our "sliding triangle" technique! Have a look here (press the play button):

Constructing Perpendicular Lines

Likewise, you can draw a perpendicular line that has to pass through a point ...

... once again, by sliding the drafting triangle along the ruler (press the play button):

Using a Ruler and Compass

You can also do those with a Ruler and Compass ... see Geometric Constructions.