The **Geometry (2D)** calculator has area, perimeter* Circles * and length equations for 2D objects including circles, ellipses, polygons, squares, rectangles, quadrilaterals, triangles, lines and curves.

For **3D **shapes and formulas for objects like spheres, cubes, cones and other 3D shapes, go to the Geometry (3D).

## Instructions

This calculator has several tabs (to the right) that contain groupings of formulas based on the different geometric shapes. Click on the tab to see the formulas that it contains. The tabs are as follows:

- Circles
- Triangles
- Quadrilaterals
- Polygons

# Description

Typically points, lines, and curves in plane geometry are referenced to an x, y coordinate system, known as the Cartesian Coordinate System.{{/footnote}}

"A plane is the two-dimensional analogue of a point (zero dimensions), a line (one dimension) and three-dimensional space."^{1}

- ^
http://en.wikipedia.org/wiki/Plane_%28geometry%29