A three-sided plane figure is called a triangle.

en.wikipedia.org/wiki/List_of_polygons

In geometry, a polygon /ˈpɒlɪɡɒn/ is traditionally a plane figure that is bounded
by a finite chain of straight line segments closing in a loop to form a closed chain
or cir...

www.reference.com/math/three-sided-polygon-called-cfd1b251ec5cec9c

A polygon with three sides is called a triangle. All triangles consist of three lines
that are not collinear and three angles. Polygons can have any number of sides,
...

mathcentral.uregina.ca/qq/database/qq.09.96/rosa1.html

What do you call a 13 sided polygon? Is there a ... There seems to be an "official"
set of names for polygons, uniformly derived from the Greek (after 4 sides). ... 3 ...

www.skillsyouneed.com/num/polygons.html

A three-sided polygon is a triangle. There are ... Scalene – all three sides, and all
three internal angles, are different. ... A five-sided shape is called a pentagon.

www.math.com/tables/geometry/polygons.htm

The number of diagonals in a polygon = 1/2 N(N-3) The number ... Two or more
of these points are called vertices. ... 46 sided polygon - Tetracontakaihexagon.

www.answers.com/Q/What_is_a_three_sided_figure_called

If the sides are all equal, and opposite sides are parallel, then the angles are all
equal (72º) and it is a 'regular hexagon'. A six sided plane figure is called a ...

faculty.kutztown.edu/schaeffe/tutorials/general/polygons.html

For polygons with 3 through 20 sides, simply add "gon" to the prefixes at the left (
although a ... Example: A 35-sided polygon is called a "triacontakaipentagon." ...

www.mathsisfun.com/shape.html

To be a regular polygon all the sides and angles must be the same: 2d triangle ·
Triangle - 3 Sides, 2d square. Square - 4 ... Any 4 sided 2D shape, 2d rectangle

owlcation.com/stem/Names-of-Geometric-Shapes-Complete-Reference-for-Elementary-and-Middle-School

Aug 29, 2016 ... A completely convex teardrop shape may be called a folium. Kidney A kidney ...
Triangle A triangle is a three-sided figure. One property of ...