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2 hexagons, 2 triangles<br />

1 hexagon, 4 triangles<br />

2 octagons, 1 square<br />

2 dodecagons, 1 triangle<br />

2 squares, 3 triangles<br />

1 decagon, 2 pentagons<br />

1 hexagon, 2 squares, 1 triangle<br />

1 dodecagon, 1 hexagon, 1 square<br />

1 dodecagon, 1 square, 2 triangles<br />

5. Answers will vary.<br />

6. Answers will vary. Example: If you start a tiling<br />

by surrounding a vertex with two pentagons<br />

and a decagon, you find that a third pentagon<br />

is necessary next to the first two. On the other<br />

side of the pentagons, you are forced to use<br />

two decagons, but those must overlap each<br />

other, which ruins the tiling.<br />

C.<br />

1<br />

The tiles are placed in<br />

order from 1 to 6; each<br />

step is forced by the<br />

available angles.<br />

2<br />

4<br />

3<br />

6<br />

5<br />

Overlap<br />

Discussion Answers<br />

A. This can be done with equilateral triangles;<br />

squares; and hexagons with triangles.<br />

B. 15-gon: triangle, decagon<br />

18-gon: triangle, nonagon (9-gon)<br />

20-gon: square, pentagon<br />

24-gon: triangle, octagon<br />

42-gon: triangle, heptagon<br />

D. Answers will vary. Most tilings will have<br />

parallel and nonparallel lines of symmetry.<br />

Nonparallel lines will form 30°, 45°, 60°, or<br />

90° angles. Centers of rotation symmetry will<br />

be found at centers of polygons, at midpoints<br />

of edges, and at vertices.They may have the<br />

same or different n-fold symmetries: twofold,<br />

three-fold, four-fold, or six-fold.<br />

Geometry Labs Notes and Answers 207<br />

© 1999 Henri Picciotto, www.MathEducationPage.org

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