The Coordinates System - Activity 2

Topic: Coordinates of points and its reflection
GeoGebra Tools: REFLECT Tool, POINT Tool

A. Locating reflections
1. Imagine putting a mirror along the y-axis. In the mirror, you will see the reflections of the points. Use the point tool [.A] to show the locations of the reflection of the points A, B, C, D, E. and F.
2. What do you notice about the coordinates of the points A, B, C, D, E and the coordinates of their reflections?

B. Using the REFLECT tool
1. The best way to find the reflection of an image is to use the REFLECT tool. Let's use this to find the reflection of the points along the x-axis.
Click the REFLECT tool, click the point you want to reflect then click the x-axis, the line of reflection. Do this for all the points.
2. What can you generalize about the signs of the coordinates of the points in each of the quadrants?

This is a Java Applet created using GeoGebra from www.geogebra.org - it looks like you don't have Java installed, please go to www.java.com

3. What can you generalize about the coordinates of the points which are reflections of each other along the y-axis?
4. What can you generalize about the coordinates of the points which are reflections of each other along the x-axis?

Erlina Ronda (http://math4teaching.com), Created with GeoGebra