Geometry

Question Analysis:  
This question combines side classification and angle classification using real-world context.
The main focus is applying the Triangle Inequality Theorem and the Pythagorean Inequality Theorem.  

Key Concept Explanation:  
- Scalene: All sides unequal (3 ≠ 5 ≠ 7).  
- Angle classification:  
 - If > , the triangle is obtuse (where is the longest side).  
 - Here, vs. . Since 49 > 34, it’s obtuse.  

Step-by-Step Solution:  
1. Side classification: 3, 5, 7 are all unequal → scalene.  
2. Angle check:  
  - Calculate → 49 > 34 → obtuse.  

Option Analysis:  
- A) Incorrect: Sides are unequal; angles are not all < 90°.  
- B) Incorrect: No two sides are equal.  
- C) Incorrect: 49 > 34 confirms obtuse, not acute.  
- D) Correct: Combines scalene and obtuse correctly.  

Common Mistakes:  
- Misapplying the Pythagorean Inequality (e.g., assuming

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