Robert Olah-Gal and Jozsef Sandor, On trigonometric proofs
of the Steiner-Lehmus theorem,
Forum Geometricorum, 9 (2009) 155--160.
Abstract: We offer a survey of some lesser known or new trigonometric proofs
of the Steiner-Lehmus theorem. A new proof of a recent refined variant is
also given.
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