Vectors and the 9-point circle

Aidan Sudbury

Research output: Contribution to journalArticleOtherpeer-review


A vector proof of the existence of the nine-point circle, a well-known theorem in Euclidean geometry, was given by D. E. Wallis in the Gazette in 1982. The part of the proof that cheated by using a geometrical construction is replaced here by a pure vector argument. Vector expressions for the centres of the in-and-ex-circles are also given.
Original languageEnglish
Pages (from-to)540 - 542
Number of pages3
JournalMathematical Gazette
Issue number534
Publication statusPublished - 2011

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