Group of Symmetry of Rectangle: Reflections & Diagonals

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SUMMARY

The group of symmetries of a rectangle includes only two reflections: across the vertical and horizontal midlines. Unlike a square, a rectangle does not possess reflections over its diagonals due to the unequal side lengths, which alter the orientation of the rectangle upon reflection. Additionally, a 180° rotation is a symmetry operation for rectangles, but it differs from reflection as it maintains the orientation of the figure. Understanding these properties is crucial for comprehending geometric symmetry.

PREREQUISITES
  • Basic understanding of geometric symmetry
  • Familiarity with reflection and rotation transformations
  • Knowledge of rectangle properties and dimensions
  • Concept of orientation in geometric figures
NEXT STEPS
  • Explore the properties of the group of symmetries of squares
  • Learn about geometric transformations in Euclidean space
  • Investigate the implications of orientation in symmetry operations
  • Study the mathematical definitions of reflection and rotation
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Students of geometry, educators teaching symmetry concepts, and mathematicians interested in the properties of geometric figures.

LagrangeEuler
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What happens if you reflect a rectangle with two different side lengths at one of its diagonal?
 
They change sides I suppose. So when I did that transformation longer side if it was horizontal it will be vertical after that transformation. Right?
 
Yes. If it was first lying down, the it's standing up afterwards, so it changed. This doesn't happen if you reflect it along the half sections parallel to the borders. By the way, rotation also makes a difference, even if rotated by ##180°##. Do you know why?
 
Have you tried these physically with a piece of paper?
 
LagrangeEuler said:
I don't not why
http://mathonline.wikidot.com/the-group-of-symmetries-of-a-rectangle
If I look figure here rotation by 180 degrees will be symmetry.
Yes, that's true. But what happens if you add an orientation, a tiny arrow which shows a direction you could walk along the rectangle? Then you see, that rotation and reflection are different, although the non-oriented figure is the same. (Not important to your original question though, but useful to remember.)
 
Thanks a lot Sir for your help.
 
Last edited:

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