chapter 7 vocabulary

glide reflection

a transformation that consists of a translation by a vector

reflection

a transformation that maps a figure(flips) over a line of symmetry;the orientation of an image and its preimage will be different

rotation

a transformation that maps every point in a plane abuot a specified point;a figure is rotated a certain number of degrees either clockwise or counterclockwise

isometry

a transformation that preserves lengths. isometries also preserve angle measures, parallel lines, and distances between points

line of reflection

a transformation that uses a line that acts like a mirror, with an image reflected in the line

theorem 7.4

a translation is an isometry

rotational symmetry

figure can be mapped onto itself by a rotation of 180 degrees or less

thereom 7.5

if lines l and m are parallel, then a relfection in line l followed by a reflection in line m is a translation

dilation

is a non-rigid trnsformatino where the mimage and the preimage are similar

angle of rotation

rays drawn from the center of rotation to a point and its image form an angle

translation

slide preimage onto its image; a transformation that maps a figure onto a ocngruent figure

terminal point

the end point

component form

the form of a vector that comvines the horizontal and vertical components of the vector

image

the new figure

transformation

the operation that maps(moves) the preimage onto the image

preimage

the orginal figure

intial point

the starting point

line of symmetry

when a transformation can be mapped onto itself by a reflection in the line

reduction

a dilation with 0<k<1

englargement

a dilation with k>1

vector

a quantity that has both direction and magnitude, and is represented by an arrow drawn between two points

theorem 7.1

a reflection is an isometry

theorem 7.3

a rotation is an isometry

theorem 7.2

a rotation is an isometry. if you turn a figure counterclockwise or clockwise it will map onto itself