Answer:
3. ΔABC ≅ ΔCDA. Reason: HL postulate
Explanation:
The two triangles are right triangles (∠B ≅ ∠D = 90°) and one leg (BC, DA) and the hypotenuse (AC, CA) are shown to be congruent. So, the HL postulate applies. The only step needed is to refer to that postulate.
Step 3. ΔABC ≅ ΔCDA. Reason: HL postulate