Two figures are said to be similar when all corresponding angles are equal, and are directly similar when all corresponding
angles are equal and described in the same rotational sense.
Any two directly similar figures are related either by a translation or by a spiral similarity (Coxeter and Greitzer
1967, p. 97).
See also Douglas-Neumann Theorem ,
Fundamental Theorem of
Directly Similar Figures ,
Homothetic ,
Inversely
Similar ,
Similar ,
Spiral
Similarity
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References Casey, J. "Two Figures Directly Similar." Supp. Ch. §2 in A
Sequel to the First Six Books of the Elements of Euclid, Containing an Easy Introduction
to Modern Geometry with Numerous Examples, 5th ed., rev. enl. Coxeter, H. S. M.
and Greitzer, S. L. Geometry
Revisited. Lachlan,
R. "Properties of Two Figures Directly Similar" and "Properties of
Three Figures Directly Similar." §213-219 and 223-143 in An
Elementary Treatise on Modern Pure Geometry. Wells, D. The
Penguin Dictionary of Curious and Interesting Geometry. Referenced on Wolfram|Alpha Directly Similar
Cite this as:
Weisstein, Eric W. "Directly Similar."
From MathWorld https://mathworld.wolfram.com/DirectlySimilar.html
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