It is a noun- the name for a 3 sided shape.
A Noun
An isosceles triangle is a noun. It is a triangle with two equal sides.
'Triangle' is a common noun. It means ' three angles'. Although we don not say it in the modern world, it could also be named a 'trigon'.
angle is the basic part of triangle
The part of speech for this particular word is a noun.
part of speech
The part of speech for "answer" is a noun.
what part of speech is beneath
adverb
The not wrong part of a triangle
The part of speech for "explicit" is an adjective.
The part of speech for "lecturer" is a noun.