UPSC Prelims 2005·GS1·science-and-technology·science and technology

An equilateral triangular plate is to be cut into n number of identical small equilateral triangular plates. Which one of the following can be possible value of n?

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Last updated 23 May 2026, 3:31 pm IST
  1. A196
  2. B216
  3. C256Correct
  4. D296

Explanation

To cut an equilateral triangular plate into 'n' identical small equilateral triangular plates, the number 'n' must be a perfect square. This is because if the side of the large triangle is divided into 'k' equal segments, the total number of small identical equilateral triangles formed will be k^2. Let's examine the given options: A) 196 = 14^2. This is a perfect square. B) 216. This is not a perfect square (14^2 = 196, 15^2 = 225). C) 256 = 16^2. This is a perfect square. D) 296. This is not a perfect square (17^2 = 289, 18^2 = 324). Both 196 and 256 are perfect squares, meaning they are mathematically possible values for 'n' under the general rule. However, in such questions, sometimes a specific method of division is implicitly assumed. A common method is recursive division: dividing an equilateral triangle into 4 smaller identical equilateral triangles by connecting the midpoints of its sides. If this process is repeated, the total number of smallest triangles will be a power of 4 (e.g., 4, 16, 64, 256, etc.). Let's check which of the perfect square options is also a power of 4: - 196 is not a power of 4 (4^3 = 64, 4^4 = 256). - 256 is 4^4 (or 16^2). This is a power of 4. Therefore, considering the possibility of recursive division, 256 is the most appropriate answer among the given options. The final answer is C.
science-and-technology: An equilateral triangular plate is to be cut into n number of identical small equilateral triangular plates. Which one o

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