Notes

1. Notes Reflection Symmetry

2. We see it all the time in the real world

3. Recall our Purpose: Our purpose is to be able to describe movement in the real world. Today we are going to be looking at movement that has a “pattern.”

4. Before we can do that… We need some prior knowledge. The graph of x = b and y = a are horizontal and vertical lines respectively.

5. For Example This is the graph of y = 3 This is the graph of x = -1

6. Make a prediction Graph y = 2, y = -1 And graph x = -3 and x = 4

7. Vocab A reflection is a transformation that flips a figure over a line. This line is referred to as the line of reflection. Like translations, reflections change the position of a figure but not its size or shape. In this example, the x axis is the line of reflection.

8. Practice Graph the given point and its image after each reflection. Graph C(4, -3 ) over the y axis. The coordinates of C’ are ____ Graph D(-5, 2) over the the line y = 2. The coordinates of D’ are ______ You try: Graph X (2,7) over the x axis. The coordinates of X’ are _____ Grapy Y (-3, -4) over the line x = 2. The coordinates of Y’ are ____

9. Reflecting shapes Like when we were translating shapes, just go point by point.

10. Identifying Lines of Symmetry If a figure can be reflected over a line so that its image matches the original figure, the figure has reflectional symmetry. The line that matches each half is called the line of symmetry. We see lines of symmetry in the real world all the time. Find one in this room.

11. Identifying Lines of Symmetry State whether or not the following have lines of symmetry. If they do have lines of symmetry, state how many they have. Make a claim: How do you know if/when a figure will have a line of symmetry. Justify it with evidence.