Answer
The proof is in the following form:
Column 1 of proof; Column 2 of proof.
Thus, we have:
1. The altitude of a right triangle is orthogonal to the base; this is the definition of an altitude.
2. The right angles are congruent; right angles are always congruent to each other
3. The angle shared by both triangles is congruent; identity property.
4. Thus, the two right triangles are similar; AA