In quadrilateral \(ABCD\), \(AD\) is congruent to \(BC\), and \(AD\) is parallel to \(BC\). Andre has written a proof to show that \(ABCD\) is a parallelogram. Fill in the blanks to complete the proof. 

Since \(AD\) is parallel to \(\underline{\hspace{.5in}1\hspace{.5in}}\), alternate interior angles \(\underline{\hspace{.5in}2\hspace{.5in}}\) and \(\underline{\hspace{.5in}3\hspace{.5in}}\) are congruent. \(AC\) is congruent to \(\underline{\hspace{.5in}4\hspace{.5in}}\) since segments are congruent to themselves. Along with the given information that \(AD\) is congruent to \(BC\), triangle \(ADC\) is congruent to \(\underline{\hspace{.5in}5\hspace{.5in}}\) by the \(\underline{\hspace{.5in}6\hspace{.5in}}\) Triangle Congruence Theorem. Since the triangles are congruent, all pairs of corresponding angles are congruent, so angle \(DCA\) is congruent to \(\underline{\hspace{.5in}7\hspace{.5in}}\). Since those alternate interior angles are congruent, \(AB\) must be parallel to \(\underline{\hspace{.5in}8\hspace{.5in}}\). Since we define a parallelogram as a quadrilateral with both pairs of opposite sides parallel, \(ABCD\) is a parallelogram.