Rotational Symmetry Flashcards

All 6 cards in this deck

What is meant by the order of rotational symmetry of a shape?

The number of times the shape fits exactly onto itself during one full turn ($360°$).

What is the order of rotational symmetry of a regular polygon with $n$ sides?

e.g. a regular hexagon

$n$.

A regular hexagon has order $6$.

True or false? A shape with no rotational symmetry has rotational symmetry of order $0$.

False. It has order $1$, because every shape fits onto itself after a full turn.

What is the order of rotational symmetry of a rectangle that is not a square?

$2$.

For a shape with rotational symmetry of order $n$, what is the smallest angle of rotation that maps it onto itself?

e.g. order $5$

$360° \div n$.

Order $5$ gives $72°$.

What are the steps to find the order of rotational symmetry of a shape?

e.g. an equilateral triangle

1. Mark the centre of the shape.
2. Turn the shape through one full turn, counting each position where it looks exactly the same: $3$ positions.
3. That count is the order: order $3$.