http://www.ck12.org Chapter 12. Rigid Transformations
12.1 Reflection Symmetry
Here you’ll learn how to determine whether or not a shape has reflection symmetry and how to draw lines of
symmetry.
What if you were asked to consider the presence of symmetry in nature? The starfish, below, is one example of
symmetry in nature. Draw in the line(s) of symmetry. After completing this Concept, you’ll be able to draw lines of
symmetry through shapes and objects like this one.
Watch This
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Click image to the left for more content.CK-12 Foundation: Chapter12ReflectionSymmetryA
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Guidance
Aline of symmetryis a line that passes through a figure such that it splits the figure into two congruent halves.
Many figures have a line of symmetry, but some do not have any lines of symmetry. Figures can also have more than
one line of symmetry. A shape hasreflection symmetrywhen it has one or more lines of symmetry.
Example A
Find all lines of symmetry for the shape below.
This figure has two lines of symmetry.
Example B
Does the figure below have reflection symmetry?
Yes, this figure has reflection symmetry.