1. Problem: Determine if the given pairs of triangles are congruent and by which theorem. 2. Recall the congruence theorems: - SSS: All three corresponding sides are congruent. - SAS: Two sides and the included angle are congruent. - ASA: Two angles and the included side are congruent. - AAS: Two angles and a non-included side are congruent. 3. (a) Triangles ABC and EFD have all three sides marked congruent. - By SSS theorem, since all corresponding sides are congruent, \(\triangle ABC \cong \triangle EFD\). 4. (b) Triangle MNO has two sides congruent to another triangle's sides and the included angle congruent. - By SAS theorem, \(\triangle MNO \cong \triangle \square\). 5. (c) Triangles GHI and \(\square\) have two angles and a side opposite one angle congruent. - By AAS theorem, \(\triangle GHI \cong \triangle \square\). Final answers: - (a) Congruent by SSS - (b) Congruent by SAS - (c) Congruent by AAS