It's a really nice idea. I wouldn't call it a proof in the rigorous sense, because you need to define trigonometric functions first and be careful you don't use

It's a really nice idea. I wouldn't call it a proof in the rigorous sense, because you need to define trigonometric functions first and be careful you don't use Pythagorean theorem to avoid circular logic. It's however perfectly fine to call it a proof for students, which is about deducing logical relation between statements. I am however, against media hype of this type of student achievements. This is very nice for high school students, and they should be showered with praise and get some notoriety in their school. For societal validation, I think it's better to have objective standards. I am not talking about this particular proof, but all the news about various "inventions" and "discoveries" made by high school students that come up every year.