Answer:
∠ACB ≅ ∠ACD
Explanation:
The SAS Postulate tells us:
If two sides and the included angle of a triangle are congruent to two sides and the included angle of another triangle, then the two triangles are congruent.
(Congruent = exactly the same)
(included angle is formed by the two known sides)
In this example we can see that 2 sides are congruent (by the dashes on the lines and the fact that both triangles share side AC), but we do not know if the included angles are congruent.
Therefore, we need to know if ∠ACB ≅ ∠ACD