Δabc is reflected across line l to form δ alblcl, and `barabar(a_l)` intersects line l at point d. which equation is not necessarily true?

Reflection of triangle ABC is nothing but flipping of triangle over a line L.

The triangle ABC is the pre image and the triangle A'B'C' is the image after reflection. D can be any point on the line L.

From the attached figure we can clearly see that

AD = D

BD = D

CD = D

The corresponding angles are equal.

So we can say that A_LD = D is not necessarily true.