Quadrilateral
a closed two-dimensional shape with four straight sides
Rhombus
a parallelogram with four congruent sides
Square
a rectangle with four congruent sides
Rectangle
a parallelogram with four right angles
Parallelogram
a quadrilateral with two pairs of parallel sides
Trapezoid
a quadrilateral with exactly one pair of parallel sides
Isosceles Triangle
a triangle with at least two sides of the same length
Scalene Triangle
a triangle with no sides of the same length
Equilateral Triangle
a triangle with three sides of the same length
Acute Angle
an angle that measures less than ninety degrees
Right Angle
an angle that measures exactly ninety degrees
Obtuse Angle
an angle that measures more than ninety degrees and less than one
hundred eighty degrees
Reflex Angle
an angle that measures more than one hundred eighty degrees
Polygon
a closed two-dimensional shape made from line segments that do not
cross each other
Concave Polygon
a polygon for which you can connect two points inside the polygon
with a line segment that passes outside the polygon
Convex Polygon
a polygon that is not concave and all the inside angles have a
measure less than 180 degrees
Pentagon
a five sided polygon
Hexagon
a six sided polygon
Octagon
an eight sided polygon
Regular Polygon
a polygon in which all sides and all angles are congruent
Congruent
exactly equal in size and shape (sides, angles and figures can be congruent)
Obtuse Triangle
a triangle with an obtuse angle
Acute Triangle
a triangle with three acute angles
Straight Angle
an angle that measures exactly one hundred and eighty degrees
Perpendicular
lines or segments that intersect to form right angles (or a square corner)
Parallel
lines or segments that stay the same distance apart and never meet or cross
Horizontal
parallel to the horizon of the earth
Vertical
perpendicular to the horizon of the earth
Point
an exact location in space
Line
a straight path that extends forever in opposite directions; named by
two endpoints
Line Segment
a part of a line with two endpoints; named by the two endpoints
Ray
a part of a line with one endpoint that extends forever in one direction
Vertex
the point on an angle or polygon where two lines or rays meet
Intersecting
lines or segments that meet or cross at one point
Right Triangle
a triangle with one right angle
One-Dimensional
a figure with only one dimension, usually length
Two-Dimensional
a figure with two dimensions, usually length and width
Three-Dimensional
a figure with three dimensions, usually length, width and height
Face
a flat surface of a three-dimensional figure
Edge
a line segment where two faces of a three-dimensional figure meet
Cube
a box-shaped solid figure that has six identical square faces
Rectangular Prism
a solid figure with two rectangular bases that are congruent and parallel