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)