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Reflections in a Coordinate Plane (Student Copy)

1. Draw a triangle with vertices at A(-3, 3) B(-2, -1), and C(-1,4). a. Reflect ABC over the y-axis to form A'B'C'

b. List the coordinates of A'B'C'. When reflecting a point over the y-axis , which coordinate remains the same? Which coordinates change? A(-3,3) A'(?,?) B(-2,-1) B'(?,?) C(-1,4) C'(?,?)

c. Write an algebraic notation to show the rule for reflecting a figure over the y-axis. (x, y) (?,?)

d. Find the side lengths and area measures of the two triangles. What do you observe?

2. Draw a triangle with vertices at A(-3, 3) B(-2, -1), and C(-1,4). a. Reflect ABC over the x-axis to form A'B'C'

b. List the coordinates of A'B'C'. When reflecting a point over the x-axis , which coordinate remains the same? Which coordinates change? A(-3,3) A'(?,?) B(-2,-1) B'(?,?) C(-1,4) C'(?,?)

c. Write an algebraic notation to show the rule for reflecting a figure over the x-axis.

d. Find the side lengths and area measures of the two triangles. What do you observe?

Practice

Without graphing, find the coordinates of the reflected image.

3.

ABC with vertices A(5, 1), B(1, 2), and C(6, 2). Reflected over the x-axis. A(5, 1) A'(?, ?) B(1, 2) B'(?, ?) C(6, 2) C'(?, ?)

4.

KLM with vertices K(2, 3), L(5, 1), and M(4, -2). Reflected over the y-axis. K(2, 3) K'(?, ?) L(5, 1) L'(?,?) M(4, -2) M'(?, ?)