In mathematics, a polygon is a two-dimensional geometric shape formed by three or more straight line segments that connect to form a closed figure.
These line segments are called sides or edges.
The points where they meet are called vertices.
Polygons are defined by their number of sides, with examples including triangles (3 sides), quadrilaterals (4 sides), pentagons (5 sides), and hexagons (6 sides).
(Note: The slide title is presented as "Definitions of Polygons".)
Page 4 — Polygons That Tessellate
Can Tessellate the Plane (no gaps or overlaps):
Equilateral Triangle
Square
Regular Hexagon
All Triangles
All Quadrilaterals
Page 5 — Polygons That cannot Tessellate
Cannot Tessellate Alone:
Regular Pentagon
Regular Octagon
Page 6 — Definitions of Tessellation
Tessellations are tiling patterns formed of shapes with no gaps in between.
Regular tessellations are formed of regular polygons.
We can see a regular polygon will tessellate by looking at the interior angles.
Keywords: Tiling patterns; No gap; Formed of regular polygons.
Additional mathematical context (conceptual, not explicitly stated in the slide):
Interior angle of a regular n-gon: θ=n180(n−2) degrees.
Around a vertex with k polygons meeting: kθ=360∘.
For common tessellations:
Triangle (n=3): θ=3180(3−2)=60∘, so k = 6 around a point.
Square (n=4): θ=4180(4−2)=90∘, so k = 4 around a point.
Hexagon (n=6): θ=6180(6−2)=120∘, so k = 3 around a point.
Conclusion: Regular tessellations with a single polygon type are possible using triangles, squares, and hexagons.
Page 7 — Shapes examples that can tessellate
Square
Triangle
Hexagon
Page 8 — Shapes examples that cannot tessellate
Pentagon
Circle
Octagon
Page 9 — Real life examples that tessellate
Honeycomb
Floor tiles
Chessboard
Page 10 — Real life examples that cannot tessellate