To determine which transformation would fail to preserve congruence, we need to consider what congruence means. Two shapes are congruent if they have the same size and shape, which can be established through transformations like translations, rotations, reflections, and resizing (dilations).
Let's analyze each option:
-
Turning the piece of plastic upside down: This is a rotation, which preserves congruence. The F will remain in the same size and shape.
-
Moving the piece of plastic down and to the left: This is a translation, which preserves congruence. The F will not change in size or shape.
-
Looking at the F through a magnifying glass: This is effectively a dilation (enlargement), which changes the size of the F while keeping its shape proportional. This does not preserve congruence because the size is altered.
-
Looking at the F through a magnifying glass and turning the piece of plastic over: This combines a dilation with a reflection. The dilation does not preserve congruence. The reflection would change the orientation, but due to the previous dilation, the result would not be congruent to the original F.
From this analysis, the correct answer is:
3. looking at the F through a magnifying glass.