There is no triangle tool in Illustrator, which to this day, boggles my mind (wtf Adobe?). I have memories of the times when I first started using Illustrator and really tried to get to know the program in depth. This was one of the things that frustrated me regularly (making a perfect, equilateral triangle) until I finally figured out a simple solution. If you use Adobe Illustrator on a regular basis, chances are you might need to create an equilateral triangle every once in a while. This may seem like a simple task, and it is, but not as easy as it should be. I'll show you how to easily make a perfect triangle path in Illustrator, and hopefully, you will have one less vector headache to deal with in the future.
1. Select the Star Tool
Yes, believe it or not, the Star Tool is what you will use to make a triangle. I know it sounds weird, but go with me here.
2. Click Once on the Artboard
By only clicking once, you will get the Star Tool Options pane. This is where you can reduce the number of points to “3.” The trick is to set one radius 2 at your desired size for your triangle, then set the other radius at exactly half. Note: It doesn't matter which radius is which. Radius 1 and 2 can be reversed as long as one is double/half the other. Choose the size of your triangle and click OK.
3. Get Rid of the Extra Anchor Points
Now that you have your triangle, you might want to get rid of the extra achor points created by the Star tool.
You can select the Subtract Anchor Point tool or hit the keyboard shortcut “-” (minus) and delete the 3 points that are in between the corners of your path.
There you have it. A perfect Triangle path in only a few easy steps, no pen tool necessary!
From here you can do anything you need to with it, like maybe reflect it and make it have the wide part at the bottom, etc. Remember that the angles in every equilateral triangle are 60 degrees, so if you need something to line up with one of the sides of your equilateral triangle, rotate that object in 60 degree intervals and you should be able to perfectly align things to your T-angle! I hope this little tip saves you some time and headache. It is often-times the little things that help the most. (from my experience)