Just looked up Quilt In A Day method. Very easy and simple.
Use rectangles cut from corner to corner for side triangles and use a triangle ruler on a strip and turn the ruler up and down to get the most triangles from the strip.
This way you can see how to line up the side triangles on the middle triangle so they fit perfect.
Do look at the video that a previous poster gave the path to the website for.
No waste with this method either compared to the wonky one that wastes lots of fabric.