• Communications of Mathematical Education
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• v.21 no.3
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• pp.385-406
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• 2007

In this paper we study on various properties of triangle's escribed circle and tetrahedron's escribed sphere. In order to accomplish our study we extract some base problems related with investigating these properties. Using the base problems we are able to prove various properties of triangle's escribed circle, and to systemize these properties. And we succeed in drawing an analogy related with tetrahedron's escribed sphere.