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Geo_1.6
Vocabulary for Geometry_1.6
Term | Definition |
---|---|
angle of rotation | The angle through which a preimage is rotated to form the image. |
center of rotation | A fixed point around which shapes move in a circular motion to a new position. |
point of symmetry | A figure that can be mapped onto itself by a rotation of 180°. |
composition of transformations | The resulting transformation when a transformation is applied to a figure and then another transformation is applied to its image. |
congruence transformation | A mapping for which a geometric figure and its image are congruent. Also called a rigid transformation or an isometry. |
glide reflection | The composition of a translation followed by a reflection in a line parallel to the transition vector. |
image | A figure that results from the transformation of a geometric figure. |
line of reflection | A line in which each point on the preimage and its corresponding point on the image are the same distance from this line. |
line of symmetry | A line that can be drawn through a plane figure so that the figure on one side is the reflection image of the figure on the opposite side. |
preimage | The graph of an object before a transformation. |
reflection | A transformation representing the flip of a figure over a point, line, or plane. A reflection in a line is a function that maps a point to its image such that if the point is on the line, then the image and the preimage are the same point, or if the point is not on the line, the line is perpendicular bisector of the segment joining the two points. |
rigid motion | The position of the image may differ from that of the preimage, but the two figure remain congruent. Reflection, translation, and rotation are the three main types. |
rotation | A transformation that turns every point of a preimage through a specified angle and direction about a fixed point, called the center of rotation. A rotation about a fixed point through an angle of x° is a function that maps a point to its image such that if the point is not the center of rotation, then the image and preimage are the same distance from the center of rotation and the measure of the angle of rotation formed by the preimage, center of rotation, and image points is x. |
rotational symmetry | A figure has symmetry if there exists a rigid motion—reflection, translation, rotation, or glide reflection—that maps the figure onto itself. |
symmetry | A figure has symmetry if there exists a rigid motion—reflection, translation, rotation, or glide reflection—that maps the figure onto itself. |
transformation | In a plane, a mapping for each point has exactly one image point and each image point has exactly one preimage point. |
translation | A transformation that moves all points of the original figure the same distance in the same direction. Also called a slide. |
translation vector | The vector in which a translation maps each point to its image. |