It is an angle.
a decagon
A geometric painting
An endpoint where two edges intersect on a polyhedron is called a vertex.
A ray.
line segment
A ray.
A five sided geometric shape is called a pentagon.
Octagon.
A ray.
That is called a dodecagon
You call it a geometric shape that is unknown to call a triangle which also affects the square because the square is not an illegal polygon, which will then lead to a Circle or a sphere as you may say it. Next it would've turned in to a rhombus with a square base. www.geometricsystems.com/shapes
compositions