Dissection of a Parallelogram into Triangles, Ross Surface Form #9


This is the ninth in a series of models of plane figures (surface forms) designed by William Wallace Ross, a school superintendent and mathematics teacher in Fremont, Ohio. The unpainted wooden parallelogram (rhomboid in Ross’s terminology) is bisected along a diagonal into two scalene triangles. A paper label attached to the model reads: Rhomboid A 4x6 Bisected. According to Ross, the model shows that if a rhomboid (parallelogram) is cut diagonally through the opposite acute angles, two equal obtuse-angled triangles result.

Compare models 1985.0112.190 through 1985.0112.202. For further information about Ross models, including references, see 1985.0112.190.

Date Made: ca 1895

Maker: Ross, W. W.

Location: Currently not on view

Place Made: United States: Ohio, Fremont

Subject: Mathematics


See more items in: Medicine and Science: Mathematics, Science & Mathematics, Arithmetic Teaching


Exhibition Location:

Credit Line: Gift of Wesleyan University

Data Source: National Museum of American History

Id Number: 1985.0112.197Catalog Number: 1985.0112.197Accession Number: 1985.0112

Object Name: geometric model

Physical Description: wood (overall material)Measurements: overall: 1 cm x 20 cm x 15 cm; 13/32 in x 7 7/8 in x 5 29/32 in

Guid: http://n2t.net/ark:/65665/ng49ca746a5-1835-704b-e053-15f76fa0b4fa

Record Id: nmah_694074

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