The definition of congruent triangles requires you to prove that three pairs of corresponding sides are congruent, as well as that three pairs of corresponding angles are congruent, before you can state the two triangles are congruent. do you think there are other ways that you might be able to prove that triangles are congruent?

Statements reasons 1. ab ? cd; ad ? bc 1. given 2. ac ? ac 2. reflexive property 3. ? adc ? ? cba 3. ? 4. ? dac ? ? bca; ? acd ? ? cab 4. cpctc 5. ? dac and ? bca are alt. int. ? s; ? acd and ? cab are alt. int. ? s 5. definition of alternate interior angles 6. ab ? cd; ad ? bc 6. converse of the alternate interior angles theorem 7. abcd is a parallelogram 7. definition of parallelogram what is the missing reason in step 3?