Microsoft interview question "Why is the manhole cover round?" Actually, I'm examining () thinking.

Because the diameter of each circle is equal, if the manhole cover is round, it will not fall into the well from any angle.

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Other shapes always have the longest inner diameter, such as rectangle, whose diagonal is longer than the side length. If the manhole cover is made into a rectangle, it is very likely to fall diagonally.

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So the manhole cover of the sewer is always round.

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This question was originally a test question when Microsoft recruited employees. The answer is this: any diameter of the round cover will not be smaller than the circle in which it is located, and the cover will not fall off. Any side of the square cover is shorter than the diagonal of the square circle where it is placed, but the cover will fall off when it is erected. This question is to examine a person's thinking ability from another angle.

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This is the figure determined after many attempts. Only the circular manhole cover can't find the diagonal, and the distance from any point to the corresponding edge is the same. As for the square, its side length is different from the diagonal length, so only the circular manhole cover is the safest when moving.

Moreover, the manhole cover with the same material has the largest circular area. If it is placed at the wellhead, no matter how it is placed, the diameter between it and the wellhead is slightly smaller, so it will not fall underground, and the workers working underground are safe.

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