From this diagram, we can see that HDG is an isosceles triangle and a property of this kind of triangle is that its base angles are always equal.
The base angles in triangle HDG are angles D and G, and by the known property, they will be equal.
So going by the above explanation, the two angles that are marked congruent will be:
![\angle HDG\text{ is congruent to }\angle HGD](https://img.qammunity.org/2023/formulas/mathematics/college/7t1qhgn9e36f6ziervt8rr1gh28b281r46.png)