The first step of an indirect proof is to assume the opposite, or negation, of the given statement.
Assume temporarily that XY ≠≅ AB.
Practice makes perfect
The first step of an indirect proof is to assume the opposite, or negation, of the given statement. Let's think about the given statement.
XY ≅ AB
To write a negation of the given statement, we need to consider how to say its opposite. Here we can do this by negating the congruence symbol.
Negation: & XY 4pt ≠≅ AB
Since the first step is to temporarily assume the opposite, we should include this fact in our sentence.
First step:
Assume temporarily thatXY 4pt ≠≅ AB.
