When we work with the Pythagorean theorem, we often write the answer as just a positive solution, even though we’re working with powers of 2, which often have positive and negative solutions. Why do we not include the negative solution?
Since we are talking about the length of the sides of a triangle, it makes no sense to say that it is, say, “minus four meters long”. In such a case, where would it even be? Would it have disappeared into a warp hole, into another dimension? Since warp holes only exist in science fiction and video games, this makes no sense in reality. So we only use the positive answer when we talk about actual units of measure.