based on the markings in the diagram, what additional information must be stated in order to prove ABC=BCD by the ASA congruence theorem?

In order to prove that triangle ABC is congruent to triangle BCD using the ASA (Angle-Side-Angle) congruence theorem, you need to provide the following additional information:

1. The measure of angle ABC.
2. The measure of angle BCD.
3. The length of one side in both triangles, such as AB and BC or AC and CD.

To apply the ASA congruence theorem, you must have two corresponding angles that are equal (angle ABC is congruent to angle BCD) and a pair of corresponding sides that are congruent (AB is congruent to BC or AC is congruent to CD).

In order to prove ABC = BCD by the ASA congruence theorem, the following additional information must be stated:

1. The measure of angle ABC is congruent to the measure of angle BCD.
2. AB is congruent to BC.

To prove that triangles ABC and BCD are congruent using the ASA (Angle-Side-Angle) congruence theorem, you would need to show that they share the same measures for two angles and the length of the side between those angles.

In the given diagram, it appears that angles ∠ABC and ∠BCD are marked as congruent. Additionally, the side AB is marked congruent to the side BC.

Therefore, you would still need additional information to prove the congruence of triangles ABC and BCD by the ASA congruence theorem. Specifically, you would need to know the measure of another angle or the length of another side. This is because the ASA congruence theorem requires knowledge of two angles and either the length of the side between them (like you already have) or the measure of another angle of the triangle.

So, to prove ABC=BCD using the ASA congruence theorem, you need to provide another angle measurement or the length of another side in addition to the given information in the diagram.