Download presentation

Presentation is loading. Please wait.

Published byGeorgia Murphy Modified over 4 years ago

1
10-9 Reflections (page 456-459) Indicators G7-Identify the line & rotation symmetries of 2-d figures to solve problems. G8-Perform reflections of 2-d figures using a variety of methods.

2
Reflections… Figures that match exactly when folded in half have line symmetry. Each fold line is called a line of symmetry. Some figures can be folded in more than one way to show symmetry.

3
You try… Determine whether each figure has line symmetry. If so how many? Where?

4
A type of transformation where a figure is flipped over the line of symmetry is a reflection. Think of a mirror image. As with translations, the original figure and reflected image are congruent. Reflection (flip) Helpful Hints! When reflecting over the x-axis, change the y- coordinate to their opposites.When reflecting over the x-axis, change the y- coordinate to their opposites. When reflecting over the y-axis, change the x- coordinate to their opposites.When reflecting over the y-axis, change the x- coordinate to their opposites.

5
Example: Reflect a figure over the x-axis. Quadrilateral QRST has vertices Q (-1,1), R (0,3), S (3,2), T (4,0). Find the coordinates of QRST after a reflection over the x-axis. Then graph the figure and its reflected image. Q R S T Q’ R’ S’ T’ The coordinates for the reflected image are Q (-1,-1), R (0,-3), S (3, -2), T (4,0). Check out the y-coordinates!

6
Example 2: Reflect a figure over the y-axis. Triangle XYZ has vertices X (1,2), Y (2,1), Z (1,-2). Find the coordinates of XYZ after a reflection over the y-axis. Then graph the figure and its reflected image. X Y Z X1X1 Y1Y1 Z1Z1 The coordinates for the reflected image are X (-1,2), Y (-2,1), Z (-1,-2). Check out the x-coordinates!

7
Example 3: Reflect a figure over the x-axis. Triangle XYZ has vertices X (1,2), Y (2,1), Z (1,-2). Find the coordinates of XYZ after a reflection over the x-axis. Then graph the figure and its reflected image. X Y Z X’ Y’ Z’ The coordinates for the reflected image are X (1,-2), Y (2,-1), Z (1,2). Check out the y-coordinates!

8
Homework 10-8 pg. 453-454 #6-12 e, 16-26 a10-8 pg. 453-454 #6-12 e, 16-26 a 10-9 pg. 459 #16-27 a10-9 pg. 459 #16-27 a

Similar presentations

© 2019 SlidePlayer.com Inc.

All rights reserved.

To make this website work, we log user data and share it with processors. To use this website, you must agree to our Privacy Policy, including cookie policy.

Ads by Google