Math vocabulary for unit 5 of sixth grade Everyday Math. This unit is focused on Geometry: Congruence, Constructions, and Parallel Lines

Acute Angle
An angle less than 90 degrees but more than 0 degrees

Adjacent Angles
Angles that have a common side and a common vertex (corner point).

Axis
Either of the two number lines used to form a coordinate grid.

Bisect
To divide into two equal parts

Concentric Circles
Circles that lie in the same plane and have the same center

Congruent
Having the same size and shape

Consecutive Angles
Two angles in a polygon with a common side

Coordinate
a pair of numbers used to determine the position of a point on a graph

Corresponding
Angles or lines of 2 different polygons that are in the same position

Image
a visual representation (of an object or scene or person or abstraction) produced on a surface

Inscribed
a circle (on the inside) of a polygon and only touches each side at exactly 1 point

Isometry Transformation
a transformation or combination of transformations which results in the image being exactly the same shape and size as the pre-image

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

Midpoint
a point that divides a segment into two congruent segments

Obtuse Angle
An angle that measures more than 90 degrees but less than 180 degrees

Ordered Number Pair
A pair of numbers used to locate a point on a coordinate grid. The fist number corresponds to a position along the horizontal axis (x), and the second number corresponds to a position along the vertical axis (y).

Origin
the point (0,0) where the x-axis and the y-axis intersect in a coordinate plane

Parallel Line Segments
Line segements that never intersect (they are always the same distance apart)

Parallel Lines
lines in the same plane that never intersect

Perpendicular
intersecting at or forming right angles

Perpendicular Bisector
A line that is perpendicular to a segment at its midpoint.

Preimage
the image before the transformation occurs

Rectangular Coordinate Grid
A device for locating points in a plane using ordered pairs or coordinates

Reflection (flip)
A transformation that produces the mirror image of a figure.

Reflex Angle
an angle that is more than 180 degrees but less than 360 degrees

Right Angle
the 90 degree angle between two perpendicular lines

Rotation (turn)
A movement of a figure that turns that figure around a fixed point.

Rough Sketch
Imperfect type of sketch used to plan drawing

Sector
a plane figure bounded by two radii and the included arc of a circle (this resembles a slice of pizza)

Skew
two lines that do NOT lie in the same plane, are not parallel, and do not intersect

Straight Angle
an angle of 180 degrees

Supplementary Angle
When the sum of the measures of a pair of angles add up to 180°

Transformation
A function that changes the position or direction of the axes of a coordinate system

Translation (slide)
A movement of a figure to a new position without turning or flipping it.

Transversal
a line that intersects two or more lines

Vertex
The common endpoint of an angle

Vertical (opposite) Angle
when two lines intersect, the angles that do not share a common side (vertical angles have equal measures)