Final answer:
In an indirect proof, you prove the truth of an 'if-then' statement by showing that assuming the opposite, 'Kk is false', leads to a contradiction, thereby validating the original statement.
Step-by-step explanation:
In an indirect proof, also known as proof by contradiction, you aim to demonstrate the truth of an if-then statement by showing that assuming the statement is false leads to a contradiction. To accomplish this, you temporarily assume the opposite of what you're trying to prove. For instance, if your original statement is 'If Kk, then Zz,' in an indirect proof, you would assume 'Kk is false' or 'not Kk.' You would then logically deduce consequences from this false assumption in an attempt to reach a contradiction. If a contradiction occurs, this invalidates the false assumption, thus proving that the original statement must be true. Therefore, the statement you should attempt to prove is false in an indirect proof is 'Kk is false'. This approach utilizes logical inference and counterexamples to show the necessity of the original statement's truth.