describing rotations

Describing Rotations

Rotational Symmetry in Nature

Rotational Symmetry in the world…

Rotation Symmetry•The compass star has

rotation symmetry.•You can turn it around its

center point to a position in which it looks identical to the original figure.

Rotation Symmetry•How many degrees will I

need to rotate point A so it will line up on point C?

•90˚ clockwise•How many degrees will I

need to rotate point A so it will line up on point E?

•180˚ clockwise

•How many degrees will I need to rotate point A so it will line up on point G?

•270˚ clockwise•How many degrees will I

need to rotate point A so it will line up on point A?

•360˚ clockwise

Rotation Symmetry

Rotational Symmetry Rules• A shape has rotational symmetry if it fits onto

itself two or more times in one complete turn.• First, determine how many times a figure can

land on itself including the full turn.• Then divide 360˚ by that number to get the

first rotational degree.• For example, the figure above can be turned

and land on itself 4 times.• 360˚ ÷ 4 = 90˚.• The rotational degrees are 90˚, 180˚, 270˚ and

360˚.

Determine if the shape has rotational symmetry. If it does, find all of its rotational symmetries.

Yes = 180˚, 360˚

Determine if the shape has rotational symmetry. If it does, find all of its rotational symmetries.

Yes = 120˚, 240˚ & 360˚

Determine if the shape has rotational symmetry. If it does, find all of its rotational symmetries. No rotational

symmetry

Determine if the shape has rotational symmetry. If it does, find all of its rotational symmetries.

Yes = 60˚, 120˚, 180˚, 240˚ 300˚, & 360˚