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Geometry. 7.1 Rigid Motion in a Plane. Goals. Identify the three basic rigid transformations. Use correct terminology in transformations. Transformations. Reflections Rotations Translations. Transformations. The “original” object is the preimage . The copy is the image. preimage.
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Geometry 7.1 Rigid Motion in a Plane
Goals • Identify the three basic rigid transformations. • Use correct terminology in transformations. Geometry 7.1 Rigid Motion in a Plane
Transformations • Reflections • Rotations • Translations Geometry 7.1 Rigid Motion in a Plane
Transformations • The “original” object is the preimage. • The copy is the image. preimage image Geometry 7.1 Rigid Motion in a Plane
Translation Preimage Image Geometry 7.1 Rigid Motion in a Plane
Reflection Preimage Image Line of Reflection Geometry 7.1 Rigid Motion in a Plane
Rotation Images Center of Rotation Preimage Geometry 7.1 Rigid Motion in a Plane
Labels • If a preimage point is A, then the corresponding image point is A’. • A’ is read “A prime”. • Preimage ABC is transformed to image A’B’C’. Geometry 7.1 Rigid Motion in a Plane
Reflection A A’ C C’ B B’ Preimage Image Geometry 7.1 Rigid Motion in a Plane
Mapping • A transformation is a mapping. • If RST is translated to XYZ, we say “RST is mapped onto XYZ”. • We write RST XYZ. Geometry 7.1 Rigid Motion in a Plane
Write the mapping for this diagram. B 90° V T 60° 90° 30° 60° A C 30° ABC ______ VTN N This mapping is a rotation. Geometry 7.1 Rigid Motion in a Plane
CD AB D V T C DA B S R A VR TV RS ABCD RSTV SRVT BADC This mapping is a reflection. Geometry 7.1 Rigid Motion in a Plane
Isometry • Iso = The same • Metry = Measure • Isometry means “The same measure”. Geometry 7.1 Rigid Motion in a Plane
Isometries preserve… • segment length • angle measure • parallel lines • distances • Transformations that are isometries are called Rigid Transformations. Geometry 7.1 Rigid Motion in a Plane
Translations, Reflections, and Rotations are ISOMETRIES. Geometry 7.1 Rigid Motion in a Plane
A A' B C B' C' Are all transformations also isometries? Segment length not preserved. Angle measures not preserved. Orientation is preserved. NO! ABC A'B'C' Geometry 7.1 Rigid Motion in a Plane
The rest of this chapter will be done by construction methods. Geometry 7.1 Rigid Motion in a Plane