This document contains notes from a math class on the topic of symmetry. It defines different types of symmetry including line symmetry, rotational symmetry, center of symmetry, and point symmetry. Examples are provided of using coordinate rules and matrix multiplication to perform rotations of 180 and 270 degrees on a quadrilateral figure. The document concludes by listing the homework problems assigned from pages 621 problems 3 through 14 and 17 through 20.

1. 9.6 Symmetry
HW pg. 621 #3­14, 17­20
February 11, 2015
Bellwork
In exercises 2 and 3, use the quadrilateral HIJK with
vertices H(3, 0), I( 1,–4), J(0, –4), K(–1, –3).
2. Use the coordinate rules to name the vertices of
the image of HIJK for a rotation of 180° about the
origin.
H′ (­3, 0), I′(­1, 4), J′(0, 4), K′(1, 3)
3. Use matrix multiplication to find the image
matrix that represents a 270° rotation of HIJK about
the origin.
–3 –1 0 1
0 –4 –4 –3
H′ I′ J′ K′
[ ]

2. 9.6 Symmetry
HW pg. 621 #3­14, 17­20
February 11, 2015
9.6 Identify Symmetry
line of symmetry: line where figure can be mapped onto itself by a
reflection.

3. 9.6 Symmetry
HW pg. 621 #3­14, 17­20
February 11, 2015
Rotational Symmetry: if figure can be mapped onto itself by a
rotation of 180 or less
Center of Symmetry: center of figure

4. 9.6 Symmetry
HW pg. 621 #3­14, 17­20
February 11, 2015
Point Symmetry: when every part has a matching part.

5. 9.6 Symmetry
HW pg. 621 #3­14, 17­20
February 11, 2015
HW
pg. 621
#3-14,
17-20 all