Download Unit 1 vocab part A

Unit 1: Similarity, Congruence, and Proofs
Vocabulary
Definition
Adjacent
next to
Altitude
Perpendicular line from a vertex of a figure to its
opposite side; height
Angle of Rotation
Measure of the angle created by the preimage
vertex to the point of rotation to the image vertex
Bisector
divides into two equal parts
Center of Dilation
a point through which a dilation takes place; all the
points of a
dilated figure are stretched or compressed through
this point
Centroid
Point of concurrency of the medians of a triangle
Collinear Points
points that lie on the same line
Complementary
sum of the measures of two angles is 90°
Compression
a transformation in which a figure becomes
smaller; compressions may be horizontal (affecting
only horizontal lengths), vertical (affecting only
vertical lengths), or both
Congruent
same shape, size, lines, and angles
Corresponding
sides of two figures that lie in the same position
Sides
relative to the figure. In transformations, the
corresponding sides are the preimage and image
sides, so AB and A2Bare corresponding sides
and so on.
Example
Diameter
Straight line passing through the center of a circle
connecting two points on the circle
Dilation
a transformation in which a figure is either enlarged
or reduced
by a scale factor in relation to a center point
Enlargement
a dilation of a figure where the scale factor is
greater than 1
Equidistant
Same distance from a reference point
Equilateral
All sides are congruent
Image
New, resulting figure after a transformation
Inscribe
To draw one figure within another so that every
vertex of the enclosed figure touches the outside
figure
Isometry
Transformation in which the preimage and image
are congruent
Line of reflection
Perpendicular bisector of the segments that
connect the corresponding vertices of the preimage
and the image
Median of a triangle
Segment joining the vertex to the midpoint of the
opposite side
Midpoint
A point that divides a line segment into two equal
parts
Non Rigid Motion
a transformation done to a figure that changes the
figure’s shape
and/or size
Parallel
lines that do not intersect
Perpendicular
lines that intersect to form a right angle.
Perpendicular
Perpendicular line constructed through the
bisector
midpoint of a segment
Preimage
Original figure before undergoing a transformation
Point of
Point of intersection of concurrent lines (3 or more
Concurrency
lines that intersect in the same point)
Proportion
An equation that equates two ratios
Radius
Line segment that extends from center of a circle to
a point on the circle. Length is half the diameter
Reduction
a dilation where the scale factor is between 0 and 1
Reflection
type of transformation that uses a line that acts like
a mirror, called the line of reflection, with an image
reflected in the line
Rigid Motion
a transformation done to a figure that maintains the
figure’s shape and size or its segment lengths and
angle measures
Rotation
Type of transformation in which a figure is turned
about a fixed point, called the center of rotation
Scale Factor
a multiple of the lengths of the sides from one
figure to the transformed figure. If the scale factor
is larger than 1, then the figure is enlarged. If the
scale factor is between 0 and 1, then the figure is
reduced.
Similar
corresponding angles are congruent and lengths of
corresponding sides are proportional
Stretch
a transformation in which a figure becomes larger;
stretches may be horizontal (affecting only
horizontal lengths), vertical (affecting only vertical
lengths), or both
Supplementary
sum of the measures of two angles is 180°
Translation
Type of transformation that maps every two points
P and Q in the plane to points P’ and Q’, so that
the following two properties are true: PP’ = QQ’,
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𝑃𝑃′ ∥𝑄𝑄′
𝑃𝑃′ and ̅̅̅̅̅
𝑄𝑄′ are collinear