Chapter 7 Vocabulary - Discovering Geometry

Image

• A rule that assigns to each point of a figure another point in the plane, called its image.
• The property that a figure coincides with itself under a rotation of less than 360 degrees.
• the original figure of a transformation
• the result of moving a figure according to a transformation.

preimage

• the original figure of a transformation
• Two-fold symmetry
• A transformation that does not preserve its size and shape.
• the result of moving a figure according to a transformation.

isometry

• the result of moving a figure according to a transformation.
• a rule that describes how to transform points on a coordinate plane
• A transformation that preserves size and shape.
• Two-fold symmetry

line of reflection

• A directed line segment from a point to its translated image.
• the line over which every point of a figure is moved by a reflection
• A transformation in which every point and its image are on opposite sides and the same distance from a fixed line.
• The property that a figure coincides with itself under a rotation of less than 360 degrees.

line of symmetry

• A transformation that preserves size and shape.
• A two-step transformation that occurs when a translation and a reflection are combined.
• a line of reflection of a figure having reflectional symmetry
• Two or more transformations that can be described as a single transformation.

Rotation

• the result of moving a figure according to a transformation.
• A rule that assigns to each point of a figure another point in the plane, called its image.
• a rule that describes how to transform points on a coordinate plane
• An isometry that is turned around a fixed point.

rotational symmetry

• The property that a figure coincides with itself under a reflection.
• Two-fold symmetry
• A transformation in which every point and its image are on opposite sides and the same distance from a fixed line.
• The property that a figure coincides with itself under a rotation of less than 360 degrees.

translation

• A two-step transformation that occurs when a translation and a reflection are combined.
• Two-fold symmetry
• the result of moving a figure according to a transformation.
• an isometry which each point is moved by the same translation vector

composition of transformations

• A transformation in which every point and its image are on opposite sides and the same distance from a fixed line.
• A transformation that preserves size and shape.
• the result of moving a figure according to a transformation.
• Two or more transformations that can be described as a single transformation.

Rigid transformation

• A directed line segment from a point to its translated image.
• A transformation that preserves its size and shape. Also called an isometry
• Two-fold symmetry
• a line of reflection of a figure having reflectional symmetry