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12.1 – Reflections 12.5 – Symmetry . M217 – Geometry. ISOMETRY. A movement or “translation” of a figure that preserves its original dimensions. Reflections Translations Rotations. Reflection – A transformation that uses a line that acts like a mirror. . Line of Reflection. C.
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12.1 – Reflections12.5 – Symmetry M217 – Geometry
ISOMETRY • A movement or “translation” of a figure that preserves its original dimensions. • Reflections • Translations • Rotations
Reflection – A transformation that uses a line that acts like a mirror. Line of Reflection C Reflection C
Reflection Properties: Over y-axis(x, y) → ( ) A (-2, 4) B (2, -1) C (0, 4) D (-3, 0)
Reflection Properties: Over x-axis(x, y) → ( ) A (-2, 4) B (2, -1) C (0, 4) D (-3, 0)
Reflection Properties: Over y=x(x, y) → ( ) A (3, 4) B (1, 1) C (-3, 2) D (-32, 11) y = x
Ex: Reflection in the line y=1 A (-1, 3) B (3, -2) C (0, 1) D (-2, 0) y = 1
Ex: Reflection in the line x = -2 Triangle ABC: A (-1, 3) B (-3, -2) C (-4, 1) x= -2
The Line of Symmetry is the imaginary line where you could fold an image and have both halves match exactly.
The Line of Symmetry is the imaginary line where you could fold an image and have both halves match exactly.
Determine the number of lines of symmetry in each logo 1. 3. 5. 4. 2.
None – Go Hawks!!! Back
One – Go Bulls!!! Back
Rotational Symmetry : if a figure can be mapped onto itself by a rotation of 180o or less
rotational symmetry : if a figure can be mapped onto itself by a rotation of 180o or less
rotational symmetry : if a figure can be mapped onto itself by a rotation of 180o or less
rotational symmetry : if a figure can be mapped onto itself by a rotation of 180o or less
Do You Get It? B’ • Is this a reflection? • How many lines of symmetry? Does it have rotational symmetry? A’ C A C’ B
Do You Get It? • If point R (-4,-5) is reflected over the y-axis, what are the coordinates of R’? • If point S (0, 2) is reflected over the line x = -5, what are the coordinates of S’? • Given points T ( -4, 3) and T’ ( -4, -2), what is the line of reflection?