Geometry

Question Analysis:  
This question involves determining the type of triangle based on its side lengths using the Converse of the Pythagorean Theorem.  
The main focus is on applying the theorem inversely to classify triangles.  

Key Concept Explanation:  
The Converse of the Pythagorean Theorem states:  
- If , the triangle is right-angled.  
- If > , it is acute.  
- If < , it is obtuse.  
(Where is the longest side.)

Step-by-Step Solution:  
1. Identify the longest side (hypotenuse candidate):  
  cm (since 13 > 12 > 5).  
2. Apply the theorem: