1

The question sounds a bit cumbersome, but it arises from this description of a product:

Outer Diameter: 78.74mm (radius)

If the word "radius" is a sub-category of "diameter", then the description is correct and clear. But if not, then the description is false and kind of ambiguous since you don't exactly know if 78.74mm is the diameter or the radius.

  • Even if radius were a sub-category of diameter, whatever that is even supposed to mean, even then the description is quite obviously not correct or clear. This is a rhetorical question based on a false premise, and as such off-topic. – RegDwigнt Jun 19 at 11:43
3

I would blame that on the bad product description, since radius is half of diameter.

  • Hello, Tymek. Please refer to the Help Center to see what constitutes a good answer here on ELU. And an acceptable question. The question has correctly now been put on hold, but answering such questions does little for the respectability of the site. – Edwin Ashworth Jun 22 at 14:02
1

Is “radius” a sub-category of “diameter”?

No, they're two different things (but that share a mathematical relationship). In other words, radius is not a kind/type of diameter, which is what a sub-category would be.

Outer Diameter: 78.74mm (radius)

I would agree with @Tymek Wojnarowski and say that that is indeed a bad product description.

  • Hello, John. Please refer to the Help Center to see what constitutes a good answer here on ELU. And an acceptable question. The question has correctly now been put on hold, but answering such questions does little for the respectability of the site. – Edwin Ashworth Jun 22 at 14:02

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