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223. How to prove the statement: "Not every triangle is acute"?

This one wants a proof. Work it on paper, read the official solution, then mark yourself honestly — the ladder only means something if the record is true.

I solved it I didn't Skip

Official solution

223. By giving an example.

The translation is provided as requested, maintaining the original text's line breaks and format.

Source: NuminaMath-1.5, licensed Apache-2.0. Statement and solution reproduced as published; topic, difficulty and ordering added by this site.