“The equal internal bisectors theorem, 1840-1940. … Many solutions or none?” A centenary account
This paper contains (i) a short history of the geometrical theorem proposed in 1840 by Prof. Lehmus of Berlin to Jacob Steiner—“If BJY, CJZ are equal bisectors of the base angles of a triangle ABC, then AB equals AC,” (ii) a selection of some half-dozen solutions from the 50 or 60 that have been given, (iii) some discussion of the logical points raised, and (iv) a list of references to the extensive literature of the subject.
1954 ◽
Vol 22
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pp. 165-264
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2015 ◽
Vol 55
(3)
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pp. 221-226
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