Symmetry

Warm-Up

• Reflect ΔABC across the y-axis.A(2, 3) B(0, -1) and C(-2, 3)

• What can we say about our pre-image and our image?

Vocabulary

• Line Symmetry – when a figure that is reflected across a line or lines maps onto itself.

• Rotational Symmetry – when a figure that is rotated a certain degree less than 360 around its center maps onto itself.

Lines of Symmetry

• How many lines of symmetry does the polygon have?

3

Rotational Symmetry

• How many lines of symmetry does the shape have?

2

Lines of Symmetry

• How many lines of symmetry does the shape have?

5

Rotational Symmetry

• What is the degree of rotational symmetry?

360÷3 = 120

Rotational Symmetry

• How many lines of symmetry does the shape have?

360÷2 = 180

Rotational Symmetry

• How many lines of symmetry does the shape have?

360÷5 = 72