gr8m_2d-geometry-8th-grade_2016-10-24.pdf - 1 8th Grade 2D...

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2 8th Grade 2D Geometry: Transformations 2016­10­24
3 Table of Contents Reflections Dilations Translations Click on a topic to go to that section Rotations Transformations Congruence & Similarity Special Pairs of Angles Symmetry Glossary Remote Exterior Angles TeacherNotes
4 Transformations Return to Table of Contents
5 Any time you move, shrink, or enlarge a figure you make a transformation . A B C A' B' C' pre­image image Transformation TeacherNotes If the figure you are moving ( pre­image ) is labeled with letters A, B, and C, you can label the points on the transformed figure ( image ) with the same letters and the prime sign.
6 The image can also be labeled with new letters as shown below. Triangle ABC is the pre­image to the reflected image triangle XYZ A B C X Y Z pre­image image Transformation
7 There are four types of transformations in this unit: Translations Rotations Reflections Dilations Transformations The first three transformations preserve the size and shape of the figure. Therefore, both the pre­image and image will be congruent . Congruent figures are same size and same shape. In other words: If your pre­image is a trapezoid, your image is a congruent trapezoid. If your pre­image is an angle, your image is an angle with the same measure. If your pre­image contains parallel lines, your image contains parallel lines.
8 Translations Return to Table of Contents
9 Translations
10 A translation is a slide that moves a figure to a different position (left, right, up or down) without changing its size or shape and without flipping or turning it. Translation You can use a slide arrow to show the direction and distance of the movement.
11 This shows a translation of pre­image ABC to image A'B'C'. Each point in the pre­image was moved right 7 and up 4. Translation
12 Click for web page Translation
Are the line segments in the pre­image and image the same length? In other words, was the size of the figure preserved? A B C D A' B' C' D' To complete a translation, move each point of the pre­image and label the new point. Example: Move the figure left 2 units and up 5 units. What are the coordinates of the pre­image and image? Answer
13 click to reveal
14 Translate pre­image ABC 2 left and 6 down. What are the coordinates of the image and pre­image? A B C

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