Chapter 10

Polygons!

lvillage.education.vic.gov.au/.../polygons.JPG

3/25- Notes: Chapter 10- sections 6&7

Symmetry and TessellationsGoals: By the end of today, you should

be able to . . . 1. Determine whether a figure has line

and/or rotational symmetry.2. Determine whether a tessellation is

regular, semi-regular or neither.3. Construct different types of tessellations

using dot paper.

Line Symmetry

• A figure has line symmetry if you can draw a _______ through the middle of it and each half is a ____________ of the other half.

http://images.google.com/imgres?imgurl=http://education.yahoo.com/homework_help/math_help/solutionimages/mini6and7gt/6/1/1/mini6and7gt_6_1_1_23_50/f-530-15-pr-2.gif&imgrefurl=http://education.yahoo.com/homework_help/math_help/problem%3Fid%3Dmini6and7gt_6_1_1_23_50&usg=__NsBBBmh9Bs6yC2aoXHMHiKU3lho=&h=300&w=300&sz=3&hl=en&start=13&tbnid=BKkj4XtxIKV9nM:&tbnh=116&tbnw=116&prev=/images%3Fq%3DLine%2BSymmetry%26gbv%3D2%26hl%3Den%26sa%3DG

Goal #1

Line Symmetry

• How do I tell if a figure has line symmetry?

• How do I tell how many lines of symmetry a figure has?

Goal #1

Rotational Symmetry

• If a figure can be ________ less than ____ so that it looks exactly the same as the ________, then it has rotational symmetry.

gwydir.demon.co.uk/jo/symmetry/exsym8.gif

Goal #1

Rotational Symmetry

• How do I tell if a figure has rotational symmetry?

• How do I tell what the degrees of rotation would be?

90°

180°

Goal #1

Pause to practice Goal #1

• Line Symmetry

1. Does a figure have it?

2. If so, how many lines of symmetry does it have?

• Rotational Symmetry1. Does a figure have

it?2. If so, what are the

degrees of each turn?

Tessellations

• Tessellation- a repeating pattern formed by polygons that have no overlapping or gapping.

• Let’s check out some more of this famous math geek/artist’s work

http://www.mcescher.com/

blauereiter.motime.com/archive/2006-04

Tessellations

• Regular- a tessellation formed by _________ regular polygon.

More regular tesselations• Semi-regular- a

tessellation formed by ______ or more regular polygons.

More semi-regular tesselations• If a tessellation has any

shapes that are not regular polygons, then it is neither.

rms.hamp.k12.wv.us/.../TessellationsOnline.html

Goal #2

Pause to practice Goal #2

• Tessellations

1. Is there any overlaps or gaps?

2. If not, what kinds of shapes make up the tesselation?