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Do Now. 1) Draw a coordinate grid (like below) and label the axes 2)Graph the point (2,1) 3 ) Translate (2,1) 4 units up and 1 unit left 4)Write the translation algebraically. Review Homework. Questions?. Reflections.
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Do Now 1) Draw a coordinate grid (like below) and label the axes 2)Graph the point (2,1) 3) Translate (2,1) 4 units up and 1 unit left 4)Write the translation algebraically
Review Homework • Questions?
Reflections Objective: Describe reflections in the coordinate plane in algebraic terms, find new coordinates of translated polygons, and graph the reflections.
∆ABC underwent a change and became ∆A’B’C’. Describe the change. C A B B’ A’ C’
Reflection • A reflection flips a figure over a line. y x
(-1, 2) Verbal to algebraic a) reflected over the x axis (x, y) (___________) New coordinates: ( )
(-1, 2) Verbal to algebraic b) Reflected across the y-axis (x, y) (___________) New coordinates: ( )
(-1, 2) Verbal to algebraic c) Reflected over the origin (x, y) (___________) New coordinates: ( )
(-1, 2) Verbal to algebraic d) Reflected over the line y = x (x, y) (___________) New coordinates: ( )
(-1, 2) Verbal to algebraic • e) Translated 3 units down and 1 unit left, then reflected over the line y = x (x, y) (___________) New coordinates: ( )
(2, 1) Algebraic to Verbal a) (x, y) (-x, y) _______________________ New coordinates: ( )
(2, 1) b) (x, y) (-x, -y) ______________________ New coordinates: ( ) Algebraic to Verbal
(2, 1) c) (x, y) (y, x) _______________________ New coordinates: ( ) Algebraic to Verbal
Special Reflections • Reflection across x– axis: • Reflection across y – axis: • Reflection over origin: • Reflection over line y = x: (x, y ) (x, -y) (x, y ) (-x, y) (x, y ) (-x, -y) (x, y ) (y, x)
1. A’B’C’ is the image produced after reflecting ABC over the line y = x. If vertex B has coordinates (s, t), what are the coordinates of B’ ? A (s, -t) B (t, s) C (-s, t) D (-s, -t)
What is the rule for the transformation formed by a translation one unit to the left and two units up followed by a reflection over the y-axis? A (x – 1, y + 2) B [-(x – 1), y + 2] C [-(x – 1), -(y – 4)] D [x – 4, -(y – 1)]
Point R(a, b) is a vertex of quadrilateral QRST. What are the coordinates of R after QRST is reflected over the x-axis? A (b, a) B (-a, b) C (-a, -b) D (a, -b)
The point A(-1, 3) is transformed according to the rule (x’y’) = (x – 2, y + 1). The image of A’ is then reflected over the origin, resulting in point A’’. What are the coordinates of A’’? A (-3, 4) B (3, -4) C (4, -3) D (-3, -4)
Homework Reflections Worksheet