1. **Problem (a):** Determine if triangles ABC and FDE are congruent given that AB = FD (one tick) and angles at C and E are marked. 2. **Formula and Rules:** To prove triangle congruence, common criteria are SSS, SAS, ASA, AAS, and HL. 3. **Analysis (a):** We have one pair of sides equal (AB = FD) and one pair of angles equal (\angle C = \angle E). However, these are not adjacent to the same side, so we cannot conclude congruence by SAS or ASA. 4. **Conclusion (a):** Not necessarily congruent. 5. **Problem (b):** Triangles MNO and RPQ each have all three sides marked equal (two ticks each). 6. **Formula and Rules:** SSS (Side-Side-Side) congruence states if all three sides of one triangle are equal to all three sides of another triangle, the triangles are congruent. 7. **Analysis (b):** Since MO = RP, ON = RQ, and MN = PQ, by SSS, \triangle MNO \cong \triangle RPQ. 8. **Conclusion (b):** Congruent by SSS. 9. **Problem (c):** Triangles GHI and JKL have two sides and one angle marked but in different positions. 10. **Formula and Rules:** SAS requires the angle to be between the two sides. ASA requires two angles and the included side. 11. **Analysis (c):** In GHI, sides GH (two ticks) and GI (one tick) and angle at I are marked. In JKL, sides JL (two ticks), LK (one tick), and angle at K are marked. The angle in GHI is at I, but in JKL the angle is at K, which is not between the two sides marked. So SAS or ASA cannot be applied. 12. **Conclusion (c):** Not necessarily congruent. **Final answers:** (a) Not necessarily congruent. (b) \(\triangle MNO \cong \triangle RPQ\) by SSS. (c) Not necessarily congruent.