a. (sb.) Geom. [f. TRI- + post-cl.L. līneālis LINEAL.] next. Also as sb. a trilineal figure.

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1745.  trans. Gregory’s Astron., I. (1726), I. 45. The infinitely small trilineal Figures.

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1807.  Hutton, Course Math., II. 115. To each add the trilineal IAE.

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1891.  Pall Mall G., 20 Oct., 6/1. Dr. Barrett … addressed the students,… he said, ‘Never mind about trilineal co-ordinates, go in for music.’

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