MathDB
Translating a triangle by a given vector

Source:

January 3, 2011
vectorgeometry unsolvedgeometry

Problem Statement

Let PP be a fixed point and TT a given triangle that contains the point PP. Translate the triangle TT by a given vector v\bold{v} and denote by TT' this new triangle. Let r,Rr, R, respectively, be the radii of the smallest disks centered at PP that contain the triangles T,TT , T', respectively. Prove that r+v3Rr + |\bold{v}| \leq 3R and find an example to show that equality can occur.