Warmup:1. Given D(-3,-1) and D'(0, –2), write the translation in coordinate notation.

Graph the following lines.

y

x

y

x

y

x

2. x = 3 3. y = –2 4. y = x

1.3 Reflections

Learning Target: I can identify and draw reflections.

(G - CO.3, G - CO.5)

Reflection

A transformation that uses a line like a mirror to reflect an image.

- This line is called the line of reflection.

- The result looks like the preimage was flipped over the line. The preimage and the image have opposite orientations.

RR✓✓

Properties of Reflections

- If a point B is on line m, then the image of B is itself (B = B').

- If a point C is not on line m, then m is the perpendicular bisector of CC'

The reflection across m that maps ∆ABC ➔∆A'B'C' can be written as

Rm(∆ABC) ➔ ∆A'B'C

A

BC

C'

A'B'

m

line of reflection

Tell whether the transformation appears to be a reflection. If yes, then draw the line of reflection.

1. 2.

A

BC

Draw the reflection of the figure across the given line. Label the vertices with proper notation.3. 4.

m

m

5. Find the coordinates of each image. a) Rx-axis(A) A' (_____, _____)

b) R x = –1(B) B' (_____, _____)

c) Ry = 1(C) C' (_____, _____)

d) Ry-axis (D) D' (_____, _____)

e) Ry = x(E) E' (_____, _____)

y

x

A

B

C

y

x

D

E

x

y

A B

C

6. Given points A(3, –1), B(5, –2) and C(4, –8), graph the reflection using the given line and state the coordinates of the image.

Rx-axis(∆ABC)

A'( ____ , ____ )

B'( ____ , ____ )

C'( ____ , ____ )

x

y

Rx = –2(∆ABC)

A'( ____ , ____ )

B'( ____ , ____ )

C'( ____ , ____ )A B

C

7. Given points A(3, –1), B(5, –2) and C(4, –8), graph the reflection using the given line and state the coordinates of the image.

y

x

Ry = x(∆ABC)

A'( ____ , ____ )

B'( ____ , ____ )

C'( ____ , ____ )A B

C

8. Given points A(3, –1), B(5, –2) and C(4, –8), graph the reflection using the given line and state the coordinates of the image.

Assignment: Geo 1.3 Reflections wkshtTuesday : MAP Testing - bring chrome books!

y

x

F

D

B

A

C

E

Exit problems

Use wolfram alpha - website to check answers!!! Just type in reflect (4,5) across y=3, for example.

Some hw answers to 1.3 wksht

1. (1, –3)

3. (–5, 1)

5. (–3, 4)

7a. (–3, 4) (–5, –2) (–8, 6)

8b. (–2, –9) (1, –7) (6, –7)

Assignment: Geo 1.3 Reflections wksht

Tuesday : MAP Testing - bring chrome books!