Maths project

Reflection symmetry is symmetry with respect to reflection.
It is the most common type of symmetry. In 2D there is an axis of symmetry, in 3D a plane of symmetry. An object or figure which is indistinguishable from its transformed image is called mirror symmetric.
The axis of symmetry of a two-dimensional figure is a line such that, if a perpendicular is constructed, any two points lying on the perpendicular at equal distances from the axis of symmetry are identical. Another way to think about it is that if the shape were to be folded in half over the axis, the two halves would be identical: the two halves are each other's mirror image. Thus a square has four axes of symmetry, because there are four different ways to fold it and have the edges all match. A circle has infinitely many axes of symmetry, for the same reason.
Example:

圖片參考：http://upload.wikimedia.org/wikipedia/commons/thumb/f/fc/Symmetry.jpg/250px-Symmetry.jpg

Rotational symmetry of order n, with respect to a particular point (in 2D) or axis (in 3D) means that rotation by an angle of 360°/n (180°, 120°, 90°, 72°, 60°, 51 3/7 °, etc.) does not change the object. Note that "1-fold" symmetry is no symmetry, and "2-fold" is the simplest symmetry, so it does mean "more than basic".
Example
order 2

圖片參考：http://www.mathsisfun.com/geometry/images/symmetry-shape-r2.gif

order 3

圖片參考：http://www.mathsisfun.com/geometry/images/symmetry-shape-r3.gif

order 4

圖片參考：http://www.mathsisfun.com/geometry/images/symmetry-shape-r4.gif

Reflectional Symmetry is 反射對稱
Rotational Symmetry is 旋轉對稱