What are some of the important shapes we encounter in geometry?

Jessica: What are some of the important shapes we encounter in geometry?
What are some of the important shapes we encounter in geometry? What is it about these shapes that we are interested in.
The first part of the question I answered right but I was wondering if some one could help me out please?

Answers and Views:

Answer by RockIt
in plane geometry, their relations and properties in a plane and their ability to mathematically model real world phenomenon. The language of circles and triangles alone goes a long way at expressing many things, when we include other shapes, its endless.

Answer by Andy D
round, square, arch

Answer by Don E Knows
Square, Rectangle, Triangle, Circle, Kite, Parallellogram, Pentagon, Hexagon, Octagon, etc.
Then there are the 3D equivalents such as Cube, Prisms, Cones, Cylinders, Spheres, and other polyhedra.

We will be interested in the perimeter of each figure (or the distance around) so we can buy the right amount of material to fence these in real-life applications.
We will be interested in the area of each figure (or how much material each contains) to buy the right amount of material to cover or pave them.
For the 3D figures, we also want to know how much material each will hold (such as liquid or gas) as the volume.

Each has formulae for these desired measurements — and that is the basis for the study of Geometry in general — the derivation and use of these formulae.