Name this mathematician whose Elements was a standard text of geometry.
The lemma named for this person states that if a prime number divides a product, then it divides a factor of that product. JÃ¡nos Bolyai and Nikolai Lobachevsky developed a system that was notable for not following all of this person's rules. A so-called orchard is named for this person because of his algorithm for finding greatest common divisors. A book he wrote states that if a line segment intersects two lines, then the lines meet on the side of the segment where the interior angle sum is less than two right angles, the last of his five postulates. Name this mathematician whose Elements was a standard text of geometry.
The lemma named for this person states that if a prime number divides a product, then it divides a factor of that product.
Euclid of Alexandria