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.