为什么三明治是三角形的?

My mother used to cut her sandwiches in half cross-wise. And I never liked that. The diagonal is what you got in the deli, in the coffee shop, the diner. And I used to love to watch them make it. Say the grilled cheese. They'd have it on the griddle. And they'd slide it off, and with that one swift stroke, cut it in half. Diagonally.

-Kemp Minifie

But triangles aren't just for haute foodies. You won't catch short-order cook Nathan "Spanky" Lewis cutting a sandwich into rectangles. He's been making sandwiches at the Tastee Diner in Bethesda, Md., for 16 years and has one word for why triangles rule: "Reputation."

Especially on a BLT or a club sandwich, he says. "If it's squared off, it doesn't even look like a sandwich." Tastee customers and waitresses rush to agree. "Sailboat sandwiches" are just the way to go.

三明治切成三角形是来源于数学上的灵感，同一片面包，切成不同的形状，得到的接触面不一样，给人的视觉也不一样。而且在数学上，三也颇受喜爱。因为有了三，才有了可比性！

It All Comes Down To Math

Consider the numbers, advises Paul Calter, emeritus professor of mathematics at Vermont Technical College. The amount of crust on a sandwich, he says, does not change, no matter how you cut it. But the amount of surface area without crust can change, depending on how many times you cut it and in which direction.

If your bread is square, and if each side is 4 inches long, you have 16 inches of crust. Cut that bread down the middle and you get 8 inches of crust-free surface. Cut that same bread diagonally, Calter calculates, and you end up with almost 11 inches of crustless surface. That's a substantial increase.

The number three has always been more popular than four, says Calter, who writes about the intersection of math, art and culture. Three is mother, father and child, he says. Three is the beginning, middle and end. Three is birth, life and death. Without three there could not be a best - only a good and a better.

Plus, Calter argues, the triangle has big fans. Plato declared the isosceles triangle to be the basic building block of the universe in his Theory of Everything. And, of course, there's the Holy Trinity and the six-pointed Star of David. As Calter points out, "a triangular sandwich can be a way of thanking the lord without actually saying grace."