maybe this drawing will help -
The Peaky and Spike triangles will make a square unit when sewn together. The height and base lengths finish the same.
The 30-60-90 triangles with a 60-60-60 triangle make a rectangle when sewn together. The height to base ratio is exactly square root of 3 to 2 - in numbers that is approximately 1.75 to 2
30-60-90 degree triangle is in red
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