With proof of contradiction, we assume the opposite of what we are
trying to prove and get a contradiction that is logical. Therefore, our
assumption is false, and we need to prove that it is true.
With proof of contrapositive, we use the rule of inference where one
infers a conditional statement from its contrapositive. For example,
“if X, then B” is what is inferred we need to construct a proof of our
claim “if not X, then not B” instead.
