There are two kinds of reasoning methods:
1, the conventional deduction method deduces a proposition from an axiom or a known proposition, and proves that the proposition is a sub-proposition of a known axiom. The key point is to clarify the meaning and conditions of the proposition and find out the equivalent meaning and conditions of the proposition. It is best to convert it into a numerical equality relationship, and then carry out symbolic calculation. This calculus method is universal, and in some special cases, it can also be transformed into intuitive geometric relations, which can be proved by intuitive geometric relations, but geometric methods need inspiration and are not universal.
2, reduction to absurdity, assuming that the proposition is not established, deducing the contradictory proposition, thus proving that the proposition is established. The application is limited, so I won't introduce it.