Any factual confirmation that helps to offer the truth of something is called as proof. There are three types of proofs named direct proofs, indirect proofs, and proofs by contradiction. Indirect proof is a type of proof in which the statement to be proved is assumed false and if the assumption tends to contrariety, then the statement assumed false has been proved to be true.
Step 1: State all possibilities.
Step 2: Assume the opposite of what you want to prove is true.
Step 3: Reason correctly until a contradiction of a given fact is obtained.
Step 4: State that negation assumed in Step 2 is false. Therefore, this follows that one of the other possibilities should be true.
Step 5: Therefore the remaining possibility is the desired conclusion.
Solving Problem 1:
Let triangle PQR is an isosceles triangle with vertex P. Solving that the angles 1 and 2 are congruent
Solving Problem 2:
Solving the following statement using an indirect proof:
ΔABC has at most one right angle.