J. Marshall Unger,
Solutions of two Japanese ellipse problems,
Forum Geometricorum, 16 (2016) 85--94.
Abstract. Two premodern Japanese theorems involving an ellipse and tangent circles are stated as problems in Fukagawa and Pedoe, Japanese Temple Geometry, 6.4.7 and 6.2.4. Neither can be proven easily by elementary means. But a proof of the second problem follows from another Japanese proposition, for which I give an original proof. It is based on the first part of an elegant proof of a generalization of the first theorem, which I present in edited form.
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