Chapter 5.4: Indirect Proof

Question 1

Indirect Proof/ Proof by Contradiction

Answer 1

In an indirect proof, one assumes that the statement to be proved is false. One then uses logical reasoning to deduce that a statement contradicts a postulate, theorem, or one of the assumptions. Once a contradiction is obtained, one concludes that the statement assumed false must be true.

Question 2

Indirect Reasoning

Answer 2

reasoning that assumes that the conclusion is false and then shows that this assumption leads to a contradiction of the hypothesis like a postulate, theorem, or corollary. Then, since the assumption has been proved false, the conclusion must be true.