Lesson 1: Symmetry in Nature and Art

Vocabulary flashcards covering core definitions, symmetry types, and formulas from Lesson 1.

Symmetry

A fundamental concept in mathematics describing a form of balance achieved when a figure remains unchanged under transformations such as reflection or rotation.

Reflection Symmetry

A type of symmetry where one half of a figure is the mirror image of the other half.

Rotational Symmetry

A type of symmetry where a figure looks the same after being rotated around a fixed point.

Line of Symmetry

The imaginary line that divides a figure into two equal mirror halves.

Center of Rotation

The fixed point around which a figure is rotated.

Angle of Rotation

The angle of turn needed for a symmetrical figure to map onto itself, calculated using the formula $\text{Angle of Rotation} = \frac{360^\text{o}}{n}$, where $n$ is the order of rotation.

Horizontal Symmetry

A type of line symmetry where the line dividing the figure into mirror halves runs horizontally from left to right.

Vertical Symmetry

A type of line symmetry where the line dividing the figure into mirror halves runs vertically from top to bottom.

Diagonal Symmetry

A type of line symmetry where the line dividing the figure into mirror halves is slanted or diagonal.

Bilateral Symmetry

A special case of line symmetry where there is only one single line of symmetry that divides a figure into two matching halves.

Order of Rotation ($n$)

The number of times a figure maps onto itself in one complete $360^\text{o}$ rotation, also referred to as $n$-fold rotational symmetry.

Regular Polygons

Polygons with equal sides and equal angles that possess both reflection and rotational symmetry.

Irregular Polygons

Polygons with unequal sides or angles that often lack both reflection and rotational symmetry.