Despite it being allegedly 'easy' to draw a Triforce in one shot, it can be difficult for those who have no idea where to start or finish. There is one part of the game whereby to progress, you have to draw a Triforce in one shot.
The game cannot recognize overlaps. Many people have been wondering how to draw it and they ended up doing the Triforce for an extremely long time with no results, no matter how many times they did it. Even if you don't draw it somewhat perfect like this, the game will recognize it as a Triforce; just remember not to overlap lines.
Basically, you follow the numbers from one through to seven. The lines are even colour coded so you know where to stop and where to start the next line. But be careful: there's a hidden timer, and when it's up, you cannot draw any more.
In other words, do it fast and do it well. Good luck!