MathDB

VietNam MO 1968-Pr.2

Source:

February 18, 2007

geometryinradiustrigonometrycircumcirclegeometric transformationreflectionquadratics

Problem Statement

L

and

M

are two parallel lines a distance

d

apart. Given

r

and

x

, construct a triangle

ABC

, with

C

on

d

, and

r

and

x

on

BC

, such that the inradius is

r

, and angle

A = x

. Calculate angles

B

and

C

in terms of

d

,

r

and

x

. If the incircle touches the side

BC

at

D

, find a relation between

BD

and

DC

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