Triangulum vs Triangle

Triangulum and Triangle both are nouns.

Word	Noun	Adjective	Verb	Adverb
Triangulum	Yes	No	No	No
Triangle	Yes	No	No	No

As nouns, Triangulum and Triangle are synonyms defined as:

Triangulum and Triangle: a small northern constellation near Perseus between Andromeda and Aries

Triangulum (noun)	Triangle (noun)
a small northern constellation near Perseus between Andromeda and Aries	a small northern constellation near Perseus between Andromeda and Aries