Editing Shape (section)

===Properties===
There are multiple ways to compare the shapes of two objects:
* [[Congruence (geometry)|Congruence]]: Two objects are ''congruent'' if one can be transformed into the other by a sequence of rotations, translations, and/or reflections.
* [[Similarity (geometry)|Similarity]]: Two objects are ''similar'' if one can be transformed into the other by a uniform scaling, together with a sequence of rotations, translations, and/or reflections.
* [[Homotopy#Isotopy|Isotopy]]: Two objects are ''isotopic'' if one can be transformed into the other by a sequence of [[Deformation (mechanics)|deformations]] that do not tear the object or put holes in it.
[[Image:Similar-geometric-shapes.svg|thumb|300px|left|Figures shown in the same color have the same shape as each other and are said to be similar.]]
Sometimes, two similar or congruent objects may be regarded as having a different shape if a reflection is required to transform one into the other. For instance, the letters "'''b'''" and "'''d'''" are a reflection of each other, and hence they are congruent and similar, but in some contexts they are not regarded as having the same shape. Sometimes, only the outline or external boundary of the object is considered to determine its shape. For instance, a hollow sphere may be considered to have the same shape as a solid sphere. [[Procrustes analysis]] is used in many sciences to determine whether or not two objects have the same shape, or to measure the difference between two shapes. In advanced mathematics, [[quasi-isometry]] can be used as a criterion to state that two shapes are approximately the same.

Simple shapes can often be classified into basic [[geometry|geometric]] objects such as a [[line (geometry)|line]], a [[curve]], a [[plane (geometry)|plane]], a [[plane figure]] (e.g. [[square (geometry)|square]] or [[circle]]), or a solid figure (e.g. [[cube]] or [[sphere]]). However, most shapes occurring in the physical world are complex. Some, such as plant structures and coastlines, may be so complicated as to defy traditional mathematical description&nbsp;– in which case they may be analyzed by [[differential geometry]], or as [[fractal]]s.

Some common shapes include: [[Circle]], [[Square]], [[Triangle]], [[Rectangle]], [[Oval]], [[Star (polygon)]], [[Rhombus]], [[Semicircle]].
Regular polygons starting at pentagon follow the naming convention of the Greek derived prefix with '-gon' suffix: Pentagon, Hexagon, Heptagon, Octagon, Nonagon, Decagon... See [[polygon]]