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1.7 Motion in Geometry. Rigid Transformations . Transformations that do not change shape or size. Preimage is the original shape Image is the shape that undergoes a transformation. preimage. image. NOTATION. Many times the vertices are labeled. We’ll call this shape ABCDEFG. B’. C’.
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Rigid Transformations • Transformations that do not change shape or size. • Preimageis the original shape • Image is the shape that undergoes a transformation preimage image
NOTATION Many times the vertices are labeled. We’ll call this shape ABCDEFG B’ C’ C B D’ D This is the PREIMAGE A A’ E’ E When the pre-image is transformed, (rotated, translated, or reflected) it becomes: A’B’C’D’E’F’G’ The image of each vertex has a small tick mark. We say ‘prime’ every time we see one of them. This notation allows us to know which is the image and which is the pre-image – which, since they are rigid – are 2 identical figures. G’ G F F’ This is the IMAGE
A little extra, free information If we started with pre-image H and it was transformed, then the image would be H’. H H’
Hang in there M C L B P N A O E D ABCDE LMNOP
Transformations • There are 3 types of rigid transformations: • Translation – shapes slide along a straight path • Rotation – shapes turn about a point • Reflection – shapes flip across a line Hello. Hello.
Translation • Shapes slide • Every point of a figure moves in a straight line, all points move the same distance and same direction.
Rotation • Rotations turn • Every point of a figure moves around a given point called the center of rotation.
Reflection Reflections flip. • In a reflection, a line plays the role of a mirror. Every point in a figure is ‘flipped’ across the line. Glide Reflection
Glide Reflection This refers to a shape that is translated and reflected… like footprints on a beach.
Summary • What is the movement of a rotation? • What does is ‘turn’ around? • What is the movement of a translation? • What does it ‘slide’ on? • What is the movement of a reflection? • What does it ‘flip’ over? • When can the pre-image and the image be a different size? • How do you notate the pre-image? (For instance segment AB) • How do you notate the image?
Summary… part 2 • If I referred to the image M’, would that be the image or preimage? • Give an example of a rotation. • Give an example of a translation. • Give an example of a reflection. • Give an example of a glide reflection. • What is the conditional of ‘my mom is beautiful’? • What is the truth value? • What is the converse of ‘my mom is beautiful’? • What is the truth value? • Are you able to write a biconditional?
Game of War • Get a partner, a pencil and one piece of paper. • Fold the paper hamburger • With a straight edge, trace the fold • On your side, put 5 war things no bigger than a dime. Don’t group them together, spread them out. • Try and hit the other person’s items by drawing a bomb on your side, folding the paper and tracing the bomb.
BONUS!!!! • I’m looking for two things….. • Tell me the relationship between the pre-image of the bomb and the image of the bomb with the fold line. • Tell me the relationship between a segment drawn between the pre-image and image of a bomb with the fold line.
Assignment Motion in Geometry packet