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10-8 Polygons and Tessellations. Learning Goal: Students will be able to determine which polygons form a tessellation. . A polygon is…. a many-sided figure a shape with three or more sides. Triangle. A triangle has three sides. 1. 3. 2. Square. A square has four sides. 4. 3. 1.
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10-8 Polygons and Tessellations Learning Goal: Students will be able to determine which polygons form a tessellation.
A polygon is… a many-sided figure a shape with three or more sides.
Triangle • A triangle has three sides. 1 3 2
Square • A square has four sides. 4 3 1 2
Pentagon • A pentagon has five sides. 1 5 2 4 3
Hexagon and Heptagon • A hexagon has six sides. (Hexagon and six both have an “x”.) • A heptagon has seven sides. heptagon hexagon
Octagon • An octagon has eight sides. Count the sides. If this octagon was red and had the word “Stop” written on it, then you would know where we see a lot of octagons.
Nonagon • An nonagon has nine sides. Count the sides. What does the word “nonagon” sound like?
Decagon • An decagon has tensides. Count the sides. How many years are in a “decade”?
How many degrees are in each polygon? • There is a formula! • (n-2)(180)= • n= the number of sides the polygon has
What is a Tessellation? • A tessellation is a tiling, kind of like the floor, except it goes on forever. • There must be no overlapping or no gaps.
Regular Tessellations • It must tile a floor (flat surface) with no gaps or overlapping. • The tiles must be regular polygons. (Remember that regular means all the sides and angles are congruent.) • Each vertex must look the same. This is a vertex.
Things We Can Tessellate with These Rules. Hexagons 120°+ 120°+120° = 360° Squares Notice that at the vertex the angles add up to 360°. 90°+ 90°+ 90°+ 90° = 360° Triangles The same thing happens here. 60°+ 60°+ 60°+ 60° + 60°+ 60° = 360°
What Won’t Tessellate Pentagons It makes a gap! 108 °+108 °+108 °= 324° Octagons Now there is an overlap. 135 °+135 °+135 °= 405° Guess what! Any regular polygon with more than six sides will overlap. So the only polygons that will work are the triangle, square, and hexagon.
Semi-Regular Tessellations Semi-regular tessellations are almost the same as regular tessellations, except you can use two or more regular polygons. 3, 6, 3, 6 3, 3, 3, 3, 6 Not a tessellation