Vertical Symmetry
Sometimes when the sun comes up, light reflecting on raindrops in clouds creates elusive rainbows. If you look closely you will find one in this photograph.
I love the simple, yet elegant vertical symmetry in the stained glass window detailing of this church.
Long Beach at low tide, looking south toward North Head.
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Horizontal Symmetry
Fishing on Odell Lake, this view of trees and their wavy reflections mesmerized me.
Though not a “mirror image” the top and bottom of this closeup of frosty dune-sand is compelling.
Two male Mallards are resting side-by-side with their beaks tucked under their wings, facing in opposite directions and centered in the shot. My best example of both vertical and horizontal symmetry in one image.
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Radial Symmetry
Radial symmetry is all about lines diverging from a common center.
Lindy Low LeCoq 
Not surprisingly Lindy, you have some wonderful examples here. My favorites though are both of your sand images. Both are quite unique especially considering the number of beach images we’ve seen through the years. Excellent imagination and creativity on those!
Thank you Tina!
Great photos, great examples. The beach and sky shots are my faves. That rainbow was tough to find. I had to zoom to maximum. I think it’s in the big cloud just left of center.
Your found it, John! Thanks for your thoughts.
Wow, Lindy. Beautiful examples of symmetry. Your first three images are stunning!
Thank you, Patti!