AIM: How can our knowledge of geometric reflections help us keep a roof from collapsing?
The unit on transformations begins with a few important definitions.
A transformation is the change of a line or point by size, position, or location. (Examples of transformations are turns, flips, and slides.)
A figure and its reflection are the same size and shape but face in opposite directions.
A reflection of a figure is called an image. The original figure is called the preimage.
A transformation that creates a figure congruent to the original is called an isometry.
Here’s an example of a reflection over the x-axis.
Here’s an example of a reflection over the y-axis.
If you look closely, you’ll see that the image and preimage in both examples are congruent. This means that reflections are isometries.
We use this fact in the classwork to explain how our roof design will keep a roof standing.