It looks difficult but is very easy.
I'll show you how to do it, just grab a pen and give it a try.
After drawing the triangle, you can round the corners to make it even cooler.
Step 1: You Need
This is all you need for the original triangle.
If you want to draw one with rounded edges you'll also need:
Not erasable pen
Step 2: Start
Try to make it as equiangular as possible.
Step 3: Parallel Lines
Step 4: Connect
Step 5: Connect
Step 6: Finish
Now your Penrose Triangle is finshed! Easy, right?
In the next step we'll round the corners to make it even more special.
Step 7: Round Corners
Just follow the instructions in the pictures.
Draw the corners round
Trace the lines with the not erasable pen
Erase the pencil lines