Quadrilateral
A four - sided polygon
Pentagon
a 5 sided polygon
Hexagon
a 6 sided polygon
Heptagon
a 7 sided polygon
Octagon
an 8 sided polygon
Nonagon
a 9 sided polygon
Decagon
a 10 sided polygon
Dodecagon
a 12 sided polygon
Polygon
A closed plane figure formed by line segments; Series of connected line segments that starts and ends at the same place and does not intercept itself anywhere in between
Regular polygon
a polygon with all sides congruent and all angles congruent; equilateral and equiangular
Diagonal
A line segment connecting two non-adjacent (non-consecutive) vertexes in a polygon
Equiangular Polygon
A polygon with all angles congruent
Equilateral Polygon
A polygon with all side lengths congruent
exterior angle measure
360 / number of sides or 180 minus one interior angle (in a regular polygon)
interior angle measure
180 minus exterior angle or (n - 2) * 180 / n
Convex polygon
A polygon such that no line containing an edge of the polygon contains a point of the interior of the polygon; points outward., no diagonal drawn outside the polygon
Concave polygon
A polygon that is not convex. It has at least one diagonal outside the polygon; "caves" inward
Polygon Angle-Sum Theorem or Sum of Interior Angles
The sum of the measures of the angles of an n-gon is (n-2) 180 or (number of sides minus 2) 180
Polygon Exterior Angle-Sum Theorem
The sum of the measures of the exterior angles of a polygon, one at each vertex, is 360.
number of triangles in a polygon
(n-2)
Vertex
The point where the sides meet; the endpoint of two segments; a common endpoint of 2 sides of a polygon
Parallelogram
a quadrilateral with 2 pairs of opposite sides that are parallel
Trapezoid
a quadrilateral having only one pair of parallel sides, called bases; the non-parallel sides are called legs;
Kite
A quadrilateral with two distinct pairs of congruent, adjacent (consecutive) sides, but opposite sides are not congruent
Altitude
A line segment drawn from one vertex to the line containing the opposite side and is perpendicular to that line. Equivalent to height.
apothem of a polygon
Distance from the center to any side of the polygon.
Coordinate Proof
Involves placing geometric figures in a coordinate plane.
height of any polygon
perpendicular distance between bases