+7 Problem: In the argument below, is the conclusion drawn true?
If a quadrilateral has two pairs of opposite sides congruent, then it is a parallelogram. If a quadrilateral has two pairs of opposite angles congruent, then it is a parallelogram. Therefore, if a quadrilateral has two pairs of opposite sides congruent, then it has two pairs of opposite angles congruent.
Answer: The form of the argument is 1) p->q 2) r->q 3) therefore p->r. The argument is not valid, but the conclusion "if a quadrilateral has two pairs of opposite sides congruent, then it has two pairs of opposite angles congruent" is in fact true
