# Unit 1 Lesson 9

- Author:
- Arpit Kesharwani

UNIT 1 • LESSON 8 ROTATION PATTERNSSetting the StageWHAT YOU WILL LEARNIn this lesson, I will rotate figures in a plane.I can...

- Introduce figures which are built by applying several transformations to one starting figure.
- Practice rotating line segments around various points.

- Demonstrating that I can describe how to move one part of a figure to another using a rigid transformation.

**FAMILY MATERIALS:**To review or build a deeper understanding of the math concepts, skills, and practices in this lesson, visit the Family Materials provided by Illustrative Mathematics Open-Up Resources. (Links to an external site.)Links to an external site.8.1: Building a QuadrilateralHere is a right isosceles triangle:- Rotate triangle ABCABC 90 degrees clockwise around BB.
- Rotate triangle ABCABC 180 degrees clockwise round BB.
- Rotate triangle ABCABC 270 degrees clockwise around BB.
- What would it look like when you rotate the four triangles 90 degrees clockwise around BB? 180 degrees? 270 degrees clockwise?

- Rotate segment ABAB 180∘180∘ around point BB.
- Rotate segment ABAB 180∘180∘ around point CC.

- Rotate segment ABAB 180∘180∘ around its midpoint. What is the image of A?
- What happens when you rotate a segment 180∘180∘?

- Describe a rigid transformation that takes triangle ABCABC to triangle CDECDE.
- Describe a rigid transformation that takes triangle ABCABC to triangle EFGEFG.
- Describe a rigid transformation that takes triangle ABCABC to triangle GHAGHA.
- Do segments ACAC, CECE, EGEG, and GAGA all have the same length? Explain your reasoning.

- The segment maps to itself (if the center of rotation is the midpoint of the segment).
- The image of the segment overlaps with the segment and lies on the same line (if the center of rotation is a point on the segment).
- The image of the segment does not overlap with the segment (if the center of rotation is
*not*on the segment).

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