 A transformation is an operation that moves or changes a geometric figure in some way to produce a new figure. The new figure is called the image. Another name for the original figure is pre-image.  A transformation can be shown using an arrow. › ∆ABC  ∆PQR

 Translation moves every point of a figure the same distance in the same direction.  Reflection uses a line of reflection to create a mirror image of the original figure.  Rotation turns a figure about a fixed point, called the center of rotation. Rays drawn from the center of rotation to a point and its image form the angle of rotation.

 Translation moves every point of a figure the same distance in the same direction.

 Reflection uses a line of reflection to create a mirror image of the original figure.  Reflection video Reflection video

 Rotation turns a figure about a fixed point, called the center of rotation. Rays drawn from the center of rotation to a point and its image form the angle of rotation.  Rotations video Rotations video  Rotations of points and shapes Rotations of points and shapes  Practice – student computers or iPads Practice

 Practice › ds/ShapeMods.html ds/ShapeMods.html  Show me/Explain Everything › Show the difference b/w:  Translations  Reflections  Rotations › Give examples of each one

 Translations, reflections and rotations are three types of congruence transformations.  A congruence transformation changes the position of the figure without changing its shape and size.  Another name for congruence transformation is isometry.  An isometry is a transformation that preserves length and angle measure.

 A dilation is a transformation that stretches or shrinks a figure to create a similar figure.  Dilatations produce similar figures (not congruent)  In a dilation, a figure is enlarged or reduced with respect to a fixed point called the center of dilation.  Dilatations are enlarged or reduced by a scale factor = the ratio of a side length of the image to the corresponding side length of the original figure. › For example the new figure may be 2x bigger (enlargement) › Or it may be ½ as big (reduction)