trans, image, reflection, line reflection
transformation
A change in position, shape, or size of a figure. Three types are translations, reflections, and rotations.
rotation
A rigid motion that turns a figure around a fixed point, called the center of rotation.
scale factor
The ratio of a length in the image to the corresponding length in the original figure.
Corresponding angles
Angles that lie on the same side of a transversal and in corresponding positions.
translation
Or slide, is a transformation that is a rigid motion that moves every point of a figure the same distance and in the same direction.
angle of rotation
The number of degrees a figure is rotated.
enlargement
A dilation with a scale factor greater than 1. After an enlargement, the image is bigger than the original figure.
Alternate interior angles
Angles that lie within a pair of lines and on opposite sides of a transversal.
image
The result of a transformation of a point, line, or figure.
center of rotation
A fixed point about which a figure is rotated.
reduction
A dilation with a scale factor less than 1. After a reduction, the image is smaller than the original figure.
Same-side interior angles
Same-side interior angles are in the interior of two lines on the same side of a transversal.
reflection
Or flip, a transformation that flips a figure across a line of reflection.
Congruent
Two two-dimensional figures are congruent, ⩭, if the second can be obtained from the first by a sequence of rotations, reflections, and translations.
Similar
A two-dimensional figure is similar, ⩬, to another two-dimensional figure if you can map one figure to the other by a sequence of rotations, reflections, translations, and dilations
Remote interior angles
The two nonadjacent interior angles corresponding to each exterior angle of a triangle.
line of reflection
A line across which a figure is reflected.
dilation
A dilation is a transformation that moves each point along the ray through the point, starting from a fixed center, and multiplies distances from the center by a common scale factors. If a vertex of a figure is the center of dilation, then the vertex and its image after the dilation are the same point.
transversal
A line that intersects two or more lines at different points.
Exterior angle of a triangle
An angle formed by a side and an extension of an adjacent side.