Question

Is an isosceles triangle a polygon?

Answer 1

Yes it is.

Explanation:

A triangle (no matter if it is isosceles, equilateral or other) is an example of a polygon.

A polyhgon is any figure bounded by a finite set of line segments closing in a loop (i.e. each vertex (an end point of a segment) is common to two consecutive segments).

A triangle is a polygon with the smallest number of segments (sides).