is a series of points that extends in two opposite directions without end

is part of a line and has 2 endpoints and all the points of the line between the endpoints

is part of a line and has one endpoint and all the points of the line on one side of the endpoint

is a flat surface with no thickness that extends without end in all directions on the surface

they lie in the same plane and have exactly one point in common

are lines in the same plane that never intersect

are neither parallel nor intersecting and lie in different planes

is formed by two rays with a common endpoint called a vertex

is the point of intersection of two sides of an angle or figure

angles are measured in these units

is an angle with a measure between 0 degrees and 90 degrees

is an angle with a measure of 90 degrees

is an angle with a measure greater than 90 degrees and less than 180 degrees

is an angle with a measure of 180 degrees

they intersect to form right angles

2 angles with the sum of their measures as 90 degrees

2 angles with the sum of their measures as 180 degrees

are formed by two intersecting lines and have two equal measures

are angles that have the same measure

is a polygon with three sides

has three acute angles

is a triangle with one obtuse angle

is a triangle with one right angle

segments that have the same length

a triangle with three congruent sides

a triangle with at least two congruent sides

is a triangle with no congruent sides

is a closed figure formed by three or more line segments that do not cross

a polygon with all sides and angles congruent

a polygon with sides that are not all congruent and/or angles that are not all congruent

is a polygon with 4 sides

is a quadrilateral with both pairs of opposite sides parallel

is a quadrilateral with exactly one pair of parallel sides

is a parallelogram with four congruent sides but different angles

is a parallelogram with four right angles but different sides

is a parallelogram with four right angles and four congruent sides

are figures with the same size and shape

are two figures that have corresponding angles and have the same measure and the lengths their corresponding sides are proportional; are the same shape but not always the same size

a line that can divide a figure so that each half is a mirror image

if a line can divide the figure so that each half is a mirror image of the other

a change in position, shape, or size of a figure; are 3 types of this that change position only are translation, reflection, and rotation

is the result of a transformation of a point, line, or figure

is a transformation that slides each point of a figure the same distance and in the same direction

is a transformation that flips a figure over a line

is a line over which a figure is reflected

is a transformation that turns a figure about a fixed point called the center of rotation

is a fixed point about which a figure is rotated