https://maximummathematics.com/books/foundational-mathematics/proof/proof-technique-indirect-proofs/index.htmlAs seen in the last section, a direct proof is a proof method where we assume the truth of the hypothesis, and show the truth of the conclusion. But the last example in that section shows that a direct proof can sometimes be quite tricky to devise. If we’re ever stuck trying to show a proposition is a theorem by taking a direct approach, we can use mathematical logic to prove an equivalent implication instead. Since we’re not proving the original implication to be a logical implication, but rather showing a logically equivalent one is, this is called an indirect approach.Hugoen-US