IM 8.1.9 Lesson: Moves in Parallel
In the applet below, describe the translation, rotation, or reflection you used above to take line to . Then plot and label and , the images of and .
In the applet below, describe the translation, rotation, or reflection you used above to take line to . Then plot and label and , the images of and .
Translate lines a and b 3 units up and 2 units to the right.
What do you notice about the changes that occur to lines a and b after the translation?
What is the same in the original and the image?
Rotate lines a and b counterclockwise 180 degrees using K as the center of rotation.
What do you notice about the changes that occur to lines a and b after the rotation?
What is the same in the original and the image?
Reflect lines a and b across line h.
What do you notice about the changes that occur to lines and after the reflection?
What is the same in the original and the image?
As you performed each transformation: What is the image of two parallel lines under a rigid transformation?What is the image of two parallel lines under a rigid transformation?
When you rotate two parallel lines, sometimes the two original lines intersect their images and form a quadrilateral.
What is the most specific thing you can say about this quadrilateral? Can it be a square? A rhombus? A rectangle that isn’t a square? Explain your reasoning.
The diagram shows a line with points labeled A, C, D, and B. On the diagram, draw the image of the line and points A, C, and B after the line has been rotated 180 degrees around point D. Label the images of the points A', B', and C'.
What is the order of all seven points? Explain or show your reasoning.
The diagram shows a line with points A and C on the line and a segment AD where D is not on the line. Rotate the figure 180 degrees about point C. Label the image of A as A' and the image of D as D'.
What do you know about the relationship between angle and angle ? Explain or show your reasoning.
The diagram shows two lines l and m that intersect at a point O with point A on l and point D on m. Rotate the figure 180 degrees around O. Label the image of A as A' and the image of D as D'.
What do you know about the relationship between the angles in the figure? Explain or show your reasoning.