Unit 3 Polygon Vocabulary

each interior angles measure formula

180(n-2)/n where n = number of sides

polygon

A closed figure formed by three or more line segments

face

A flat surface of a polyhedron

concave polygon

A polygon that has at least one diagonal with points outside the polygon.

irregular polygons

A polygon which has at least two sides with different lengths or two angles with different measures

n-gon

A polygon with n sides. For example, an 8-gon is another name for an octagon.

regular polygons

A regular polygon has all sides congruent and all angles congruent

sum of interior angles of a polygon

Sum=180(n-2), where n is the number of sides.

Area

The number of square units required to cover a surface.

vertices

The point of intersection of two sides of a polygon. The point of intersection of three edges of a space figure.

line of symmetry

a line that divides a figure into two halves that are mirror images of each other

convex polygon

a polygon such that no line containing a side of the polygon contains a point in the interior of the polygon//all interior angles are less than 180 degrees

polyhedron

a solid figure bounded by plane polygons or faces

equilangular

all angles are congruent

equilateral

all sides are congruent

rotational symmetry

if you can rotate a figure 180 degrees or less so that it matches the original

center of symmetry

the center of rotation in a figure that has rotational symmetry

perimeter

the distance around a polygon

Edges

the line segments where the faces intersect

degree of rotational symmetry

the number of degrees a figure must be turned to create a congruent figure (360 divided by number of sides)