I am trying to create an equilateral triangle with a smaller equilateral triangle cut directly from it's center, like a stencil. I have made the triangle and used the Path Selection Tool to copy it and use it as a subtraction. The second triangle is now 50% smaller:
How can I align the smaller triangle to the exact center of the larger one?
Well this is one of those cases where its about 100 times faster to do this in Illustrator. But given that you must use Photoshop for this here is how you find center of mass of the triangle, which is what your after:
Image 1: Triangle and its center of mass.
Where the edges cross is where your triangle has its center of mass.
Now I really recommend you do this in Illustrator instead, if you have it. Its infinitely easier to be accurate. You can always paste the shape into Photoshop.
Image 2: Result
A better idea requiring much less effort is to select the shape tool, and choose custom shape. Within the options settings for the shape tool, select for it to be represented as a path. Right click on the canvas, and find the triangle depicted below. It is perfectly aligned to the center with the cut-out you requested. Stroke and or fill to your liking in paths dialog located behind the layers display.
