Euclidean theorem
# Euclidean theorem

Euclidean theorem may refer to:

* Any theorem in Euclidean geometry
* Any theorem in Euclid's Elements, and in particular:
   * Euclid's theorem that there are infinitely many prime numbers
   * Euclid's lemma, also called Euclid's first theorem, on the prime factors of products
   * The Euclid–Euler theorem characterizing the even perfect numbers
   * Geometric mean theorem about right triangle altitude
