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Geometry. Lesson 4 – 7 Congruence Transformations. Objective: Identify reflections, translations, and rotations. Verify congruence after a congruence transformation. Transformations. Transformations – An operation that maps an original figure ( preimage ) onto a new figure ( image ).
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Geometry Lesson 4 – 7 Congruence Transformations Objective: Identify reflections, translations, and rotations. Verify congruence after a congruence transformation.
Transformations • Transformations – • An operation that maps an original figure (preimage) onto a new figure (image).
Congruence Transformations • AKA rigid transformations • AKA isometric (isometry) • The position of the image may differ from that of the preimage, but the two figures remain congruent.
Types of Congruence Transformations • Reflection • A transformation over a line called the line of reflection. A flip over a line.
Types of Congruence Transformations • Translation • A transformation that moves all points of the original figure the same distance in the same direction. A slide of the points
Types of Congruence Transformations • Rotation • A transformation around a fixed point called the center of rotation. Each point of the original figure and it image are the same distance from the center. A turn about a point.
Identify the type of congruence transformation shown as a reflection, translation, or rotation. Rotation Reflection Translation
Identify the type of congruence transformation shown as a reflection, translation, or rotation. Translation Rotation Reflection
Identify the type of congruence transformation shown in the diagram as a reflection, translation, or rotation. Rotation
Identify the type of congruence transformation shown in the diagram as a reflection, translation, or rotation. Translation Reflection
Verify Congruence after Transformation • Triangle XZY with vertices X (2, -8), Z (6, -7), and Y(4, -2) is a transformation of Triangle ABC with vertices A (2, 8), B (6, 7), and C (4, 2). Graph the original figure and its image. Identify the transformation and verify that it is a congruence transformation. Reflection Cont…
Verify the triangles are congruent • Since no angles are known we will prove congruence by SSS.
Homework • Pg. 297 1 – 6 all, 8 – 28 E, 32, 38 – 42 E, 46 – 50 E