The letter H is symmetric with respect to two different lines, as shown by the dotted lines in the figure above. Which of the following letters is symmetric with respect to at least two different lines?
This question is easy if you can visualize straight lines on the various letters. Imagine a horizontal line going through the center of the letter X - this line produces a mirror image above and below the line. Then, imagine a vertical line also through the center of the letter. Now you have a mirror image to the left and right of the line. This is the only letter (of the choices given) that has two such lines of symmetry, so the correct answer is D.
If you are interested in the symmetry properties of the rest of the alphabet, check out The Symmetry of Capital Letters. Notice the discussion of the letter X at the end of the page.
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