Actually, there was a classic short story somewhere where a plot line involved alien geometry and I'm pretty sure the key phrase was very close to "three perfectly parallel lines intersecting at ninety degree angles to form a perfect square with seven triangular sides."
(Ah, I miss the "sorta old days" when reading short stories from the "Golden Age" was fun. Best guesses are Mimsy Were the Borogoves or And He Built a Crooked House.)