File:Twocolumnproof.png

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DescriptionTwocolumnproof.png	English: Taken from Patricio G. Herbst, "Establishing a Custom of Proving in American School Geometry: Evolution of the Two-Column Proof in the Early Twentieth Century", Educational Studies in Mathematics, Vol. 49, No. 3 (2002), pp. 283-312. Herbst says, "Photographed by the author from Schulze and Sevenoak, 1913, p. 53, Macmillan publishers." This paper is available from https://www.jstor.org/stable/3483034
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2008-10-05 20:37 CBM 437×404× (159952 bytes) {{PD-us}} == Source == Taken from Patricio G. Herbst, "Establishing a Custom of Proving in American School Geometry: Evolution of the Two-Column Proof in the Early Twentieth Century", ''Educational Studies in Mathematics'', Vol. 49, No. 3 (2002), pp. 28

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	Date/Time	Thumbnail	Dimensions	User	Comment
current	10:02, 25 July 2009		437 × 404 (156 KB)	wikimediacommons>File Upload Bot (Magnus Manske)	{{BotMoveToCommons\|en.wikipedia\|year={{subst:CURRENTYEAR}}\|month={{subst:CURRENTMONTHNAME}}\|day={{subst:CURRENTDAY}}}} {{Information \|Description={{en\|Taken from Patricio G. Herbst, "Establishing a Custom of Proving in American School Geometry: Evolution

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