20 equilateral triangular sides
An icosahedron is a polyhedron has 20 faces, and is a 3D shape.
Probably a mis-spelling of icosahedron. That is a 3-dimensional figure bounded by 20 regular (equilateral) triangles.
a crescent has 19 sides
Mo such shape/thing as a 'polgon'. If you mean ' polygon'. The word 'polygon' means a 2-dimensional shape (--gon) of many sides (poly--). So the word 'polygon' mean an many sided shape. For a specific number of sides it becomes;- trigon ( triangle) 3 sides quadragon ( quadrilateral ) 4 sides pentagon 5 sides et seq.,
10 sides.
There is no formula for how many sides there are in a polygon; the name of the polygon shows how many sides it has.
How many sides does a Decahedron Have
3Three.
Polygon means "many sides."
"no" sides.
4 sides
How many parallel sides has a trapezium?