PRE-ALGEBRA “Symmetry and Reflections” (9-9) A figure has symmetry when one half is a mirror image of the other half (in other words, both halves are congruent). What is “reflectional symmetry”? What is a “line of symmetry”. Example: In the pictures below, the butterfly has one line of symmetry and the snowflake has six line of symmetry. What is a “reflection”. Example: In the figure below,  A’B’C’ is a reflection of  ABC., because reflected points are the same distance from the line of reflection (A’ and A’ are 4 units from “y”, B and B’ are 3 units from “y”, C and C’ are 2 units from “y”). Note:  A’B’C’   ABC. The line of symmetry divides a figure into two congruent halves. Note: A figure can have more than one line of symmetry. A reflection is transformation in which a figure is flipped over a line of reflection, so both sides of the line of reflection are mirror images of one another

PRE-ALGEBRA Identify the lines of symmetry. Tell how many there are. a. b. 8 lines of symmetry Symmetry and Reflections LESSON 9-9 Additional Examples 2 lines of symmetry

PRE-ALGEBRA Reflect the other endpoint, G, which is 4 units away from the x-axis. Since F is 2 units below the x-axis, F is 2 units above the x-axis. Draw F G. FG has endpoints F(–4, –2) and G(–2, –4). Graph FG and the image of FG after a reflection over the x-axis. Symmetry and Reflections LESSON 9-9 Additional Examples

PRE-ALGEBRA Graph y = –1 (in red). Reflect the other endpoint, G, which is 3 units away from the x- axis. Since F is 1 unit below the red line, F is 1 unit above the red line. Draw F G. FG has endpoints F(–4, –2) and G(–2, –4). Graph FG and the image of FG after a reflection over y = –1. Symmetry and Reflections LESSON 9-9 Additional Examples