The distance around a figure.
Perimeter
An angle smaller than a right angle.
Acute
A triangle with two equal sides.
Isosceles
Two lines that form a right angle.
Perpendicular
A line segment formed by two sides of a 3-D figure.
Edge
A four-sided figure.
Quadrilateral
An angle larger than a right angle.
Obtuse
A triangle with three equal sides.
Equilateral
A six-sided figure
Hexagon
One side of a three dimensional figure
Face
The total number of square units that a figure covers.
Area
Two lines that will never intersect.
Parallel
A triangle with no equal sides.
Scalene
An angular point on a polygon
Vertex
A straight line in which one side is a point and the other an arrow.
Ray
Sides of a figure that are across from each other.
Opposite
A parallelogram with equal side lengths.
Rhombus (or square)
A line in which a figure can be folded so that both sides are the same.
Line of Symmetry
Any polygon in which all of the sides and angles are equivalent.
Regular Polygon
An angle between 180 degrees and 360 degrees
Reflex
A rectangle with four sides that are the same length.
Square
A quadrilateral with one pair of parallel sides.
Trapezoid
Two sides that are next to each other.
Adjacent
A figure that includes two or more polygons inside of it.
The distance from the center of a circle to any point on the circle.
Radius