1.6 2-D Figures
Please see book for examples (pages 56-66)
Important definitions
 Polygons
 Closed figure formed by a finite
number of coplanar segments called
sides
 Sides that have a common end point
are noncolinear
 Each sides intersects exactly two
other sides, but only at their
endpoints
 Do not have common interior points
Examples
NonExamples
 Concave vs. Convex Polygon
 Concave polygons have lines that
contain points in the interior of the
polygon
 Convex polygons do not have any
lines with points in the interior of the
polygon
 Equilateral/Equiangular Polygon
 In an equilateral polygon, all sides
are congruent
 In an equiangular polygon, all
angles are congruent
 Regular vs. Irregular Polygon
 Any convex polygon that is both
equilateral and equiangular is
considered a Regular Polygon
 An Irregular polygon therefore is a
polygon that is not regular
Regular Polygon
Irregular Polygon
P=s+s+s+s
C = 2πr
P = 4s
C = πd
 Perimeter vs. Circumference
 Perimeter if the sum of the lengths
of all sides of the polygon
 Circumference is the distance around
the circle
 Area
 The number of Square units needed
to cover a surface