Geometry Terms

Angle of Rotation

a measurement of the amount, the angle, by which a figure is rotated counterclockwise about a fixed point, often the center of a circle

Center of Rotation

a fixed point around which shapes move in a circular motion to a new position

Center of Dilation

the fixed point about which the figure is enlarged or reduced

Center of Symmetry

the center of rotation in a figure that has rotational symmetry

Composition of transformations

a combination of two or more transformations

Congruence transformations (rigid motions)

if you slide, flip, or turn a triangle, the size and shape do not change

Dilation

a transformation that changes the size of an object, but not the shape.

Glide reflection

the composition of a translation and a reflection across a line parallel to the translation vector

Image

the new position of a point, a line, a line segment, or a figure after a transformation

Pre-image

the original figure in a transformation

Line of Reflection

a line that a figure is flipped across to create a mirror image of the original figure