Module 2 Lesson 2 Reflections Reflections

Real-life reflections Animation Architecture Graphic Design

Reflections Reflection: a transformation in which a figure is flipped over a line of reflection. This line can be thought of as a mirror in which the image is a reflection of the pre-image. A reflection creates a mirror image of each point of a figure. For this class, our line of reflection will be either the x-axis or the y-axis on a coordinate grid.

Reflection Tell whether the red figure is a reflection of the blue figure. This figure is a reflection. This figure is not a reflection.

Example H Reflect over the x-axis E Y

Reflecting over the y-axis Coordinates of each vertex of a triangle and its image are shown. Do you see a pattern in the change from the preimage to the image? Preimage Image Preimage Image (-3, -2) (3, -2) (-10, 0) (10, 0) (-2, 3) (2, 3) When a point is reflected over the y-axis, its x-coordinate is multiplied by -1.

Reflecting over the x-axis Coordinates of each vertex of a triangle and its image. Do you see a pattern in the change from the preimage to the image? Preimage Image (-2, 2) (-2, -2) (-1, 7) (-1, -7) (6, 5) (6, -5) When a point is reflected over the x-axis, its y-coordinate is multiplied by -1.

Your turn! Graph the triangle with vertices J(0, 1), K(1, 4), and L( 5, 2). Reflect the triangle over the y-axis and label it.

Your turn! Graph the quadrilateral with vertices S(-3,2), T(-1, 4), U(-4, 5), and V(-5, 3). Reflect the quadrilateral over the x-axis and label it.

Translation Game http://www.mathplayground.com/ShapeMods/ShapeMods.html http://staff.argyll.epsb.ca/jreed/math9/strand3/transformations.htm