The first step of an indirect proof is to assume the opposite, or negation, of the given statement.
Assume temporarily that the side is less than 2 ft long.
Practice makes perfect
The first step of an indirect proof is to assume the opposite, or negate the statement. Let's think about the given statement.
The side is at least2 ft long.
To negate a statement, we need to consider how to say the opposite. Here we can change at least into less than to negate the sentence.
Negation: & The side is less than2 ft long.
Since the first step is to temporarily assume the opposite, we should include this fact in our sentence.
First step: & Assume temporarily that the side & is less than2 ft long.
