PRINCIPIA · THEOREM
Similar triangles — corresponding altitude / median / angle-bisector ratios = similarity ratio
Dependencies: AA similarity, SAS / SSS similarity (SSS and SAS similarity tests).
Statement
Let with similarity ratio , i.e.
Let , , denote, respectively, the altitude, median, and Angle bisector ⇔ equidistant from sides length from vertex in (each with foot on side ); and , , the corresponding cevians of the same kind in . Then
That is, every interior segment defined by similar triangles in a "corresponding" manner scales by the similarity ratio .

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