Geometry and Trigonometry

Basics of Geometry

What is an indirect proof?

Direct proofs start with a true statement and then set out to prove that a conclusion is true. But there is also a method called the indirect proof in which indirect reasoning is used. First, assume that the conclusion is false; then show that this assumption leads to a contradiction of the hypothesis or some other accepted fact, such as a postulate or theorem. Therefore, if the assumption is proved false, the conclusion has been proved—indirectly—to be true.


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