Difficulty: Easy
Correct Answer: 13 m
Explanation:
Introduction / Context:The longest rod/pole that fits inside a cuboidal room equals the space diagonal of the cuboid. This is a classic 3D mensuration result derived from the Pythagorean theorem applied twice.
Given Data / Assumptions:
Concept / Approach:Space diagonal d of a cuboid with dimensions l, b, h is given by d = sqrt(l^2 + b^2 + h^2).
Step-by-Step Solution:
d = sqrt(12^2 + 4^2 + 3^2) = sqrt(144 + 16 + 9) = sqrt(169) = 13 mVerification / Alternative check:The diagonal of the floor is sqrt(12^2 + 4^2) = sqrt(160). Extending to 3D with height 3 gives sqrt(160 + 9) = sqrt(169) = 13, confirming the result.
Why Other Options Are Wrong:14 m, 15 m, and 16 m exceed the exact space diagonal and cannot fit entirely within the room.
Common Pitfalls:Confusing the space diagonal with a face diagonal (e.g., sqrt(12^2 + 4^2)) leads to an underestimate. Always include all three dimensions.
Final Answer:13 m
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