Track / Stage 4 / 140 of 340 #400 of 1964

Problem 400

AMC 12 late, AIME early

Combinatorics Difficulty 4.8 Find the answer

3. For a regular $n$ -sided pyramid, if the side length of the base and the side length of the lateral edge are equal, then the set of values for $n$ is $\qquad$

Translate the above text into English, please retain the original text's line breaks and format, and output the translation result directly.

Your answer

A number or a short expression. Spacing, $ signs and \frac vs / are all fine.

Official solution

$\{3,4,5\}$ ;

Source: NuminaMath-1.5, licensed Apache-2.0. Statement and solution reproduced as published; topic, difficulty and ordering added by this site.