Abeka 8th Grade Math, Unit 8.1 - 8.13
rhombus
a parallelogram having four congruent sides
rectangle
a parallelogram having four right angles
arc
a part of the circle
center
a point in the middle of a circle that is equidistant from all points on the circle
ray
a portion of a line having one endpoint
line segment
a portion of a line having two end points by which it is named
parallelogram
a quadrilateral having both pairs of opposite sides parallel to each other
trapezoid
a quadrilateral having only one pair of opposite sides that are parallel
square
a rectangle having four congruent sides
heptagon
a seven-sided polygon
circle
a simple closed curve
polygon
a simple closed shape made up of line segments
hexagon
a six-sided polygon
triangle
a three-sided polygon
degree
a unit used to measure the amount of rotation between rays
octagon
an eight-sided polygon
protractor
an instrument in the shape of a semicircle that is used to draw or measure angles
compass
an instrument used to draw circles
central angle
angle at the center of a circle where two radii meet
congruent angles
angles containing the same number of degrees
straight angle
contains 180 degrees
right angle
contains 90 degrees
acute angle
contains less than 90 degrees
reflex angle
contains more than 180 degrees but less than 360 degrees
obtuse angle
contains more than 90 degrees but less than 180 degrees
semicircle
exactly half of a circle
line
extends infinitely in two opposite directions and is named by using capital letter which are points on the line or a single lower case letter
vertical angles
formed by two intersecting lines
side
line segments of a polygon
congruent line segments
line segments of equal length
parallel lines
lines in the same plane that never intersect
perpendicular lines
lines that form a right angle when they intersect
intersecting lines
lines that have one point in common
congruent shapes
shapes that have the same shape and size
similar shapes
shapes that have the same shape but not the same size
vertex
the common endpoint of an angle
radius
the length of a straight line drawn from the center to a point on the circle
vertex of a polygon
the point where two sides of a polygon meet
sides
the two rays of an angle
bisect
to divide the angle into two congruent angles
adjacent angles
two angles with a common ray between them
supplementary angles
two angles with a sum of 180 degrees
complementary angles
two angles with a sum of 90 degrees
skew lines
two lines in space their neither intersect nor are parallel
angle
two rays that share a common endpoint
straightedge
used to draw a straight line if a certain length is not required
point
a loaction in space represented by a dot and named by using a capital letter
closed curve
a curve that begins and ends at the same point
simple closed curve
a curve that has no point of intersection
plane geometric figure
a figure in which all the points are in the same plane
geometric figure
a figure made up of points
pentagon
a five-sided polygon
plane
a flat surface that extends infinitely in all directions
quadrilateral
a four-sided polygon
curve
a geometric figure that can be drawn without removing the drawing instrument from the paper
diameter
a line segment that goes through the center of the circle ahd has both endpoints on the circle
chord
a line segment whose endpoints are on the circl