How many lines of symmetry to these regular polygons have? Bell Ringer How many lines of symmetry to these regular polygons have? 5 4 3 Do you see a pattern? 6 8

An informal Introduction to Geometry

Definitions Topic: Symmetry symmetric line of symmetry Name: Date: When you can fold a figure in half so that the two halves fit exactly on top of each other, the shape is symmetric. line of symmetry The line that contains the fold

Examples The horizontal line through the second T is not a line of symmetry vertical line of symmetry

Symmetry

To be a line of symmetry, the shape must have two halves that match exactly. When you trace a heart onto a piece of folded paper, and then cut it out, the two half hearts make a whole heart. The two halves are symmetrical.

Which of these flags have a line of symmetry? United States of America Canada No Maryland England No

What about these math symbols? Do they have symmetry? + - Yes Yes - x Yes Yes

# 2. Describe the lines of symmetry of a circle. To Do With Your Partner # 1. Which other letters are symmetric? Which letters are both horizontally symmetric and vertically symmetric? solution next slide # 2. Describe the lines of symmetry of a circle. any line through the center of the circle

A B C D E FG H I J K L M N O P Q R S T U V W X Y Z You can look to see if your name has symmetrical letters in it too! A B C D E FG H I J K L M N O P Q R S T U V W X Y Z Infinite number

Definitions Prism A solid formed by translating a given base shape into the third dimension along a line. Part of a line that contains two endpoints and all the points between the two endpoints Line segment

Lines in the same plane that do not intersect. Parallel Lines Planes in the same space that do not intersect Parallel Planes Where do you see parallel lines in the classroom?

Homework p.14 # 5