A fact from Roberts's triangle theorem appeared on Wikipedia's Main Page in the Did you know column on 6 November 2022 (check views). The text of the entry was as follows:
Did you know... that it took 90 years to replace the "unconvincing" original proof of Roberts's triangle theorem, on the number of triangles formed by systems of lines, with a correct proof?
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The following is an archived discussion of the DYK nomination of the article below. Please do not modify this page. Subsequent comments should be made on the appropriate discussion page (such as this nomination's talk page, the article's talk page or Wikipedia talk:Did you know), unless there is consensus to re-open the discussion at this page. No further edits should be made to this page.
The result was: promoted by RoySmith (talk) 22:28, 2 November 2022 (UTC)[reply]
... that it took 90 years to replace the "unconvincing" original proof of Roberts's triangle theorem, on the number of triangles formed by systems of lines, with a correct proof? Source: https://faculty.washington.edu/moishe/branko/BG223.How.many.triangles.pdf ("Unconvincing" is a quote from this source. the 90 years is a trivial calculation based on the 1889 date of the original proof and 1979 date of what Grünbaum calls the first correct proof).
Overall: @David Eppstein: good article. However, i'm not seeing where in the source has the word "unconvincing". Could you provide another source? Onegreatjoke (talk) 15:22, 1 November 2022 (UTC)[reply]
@Onegreatjoke: oops, sorry about that. The "unconvincing" quote is in the Fejes Toth source (doi:10.1080/00029890.1975.11993840, JSTOR2318414, probably paywalled). Fejes Toth credits it to an earlier work of Grünbaum [1] which uses slightly different wording; the hook uses the wording from Fejes Toth. Additional footnotes added for proper credit for the quote. —David Eppstein (talk) 15:39, 1 November 2022 (UTC)[reply]