MathDB

Inequality for angle

Source: Romania TST 3 2009, Problem 1

May 4, 2012

inequalitiesgeometry proposedgeometry

Problem Statement

Let

ABCD

be a circumscribed quadrilateral such that

N

,

M

be the common point of

AB

and

CD

and

N

be the common point of

AC

and

BD

. Show that

90^{\circ}<m(\angle AND)<90^{\circ}+\frac{1}{2}m(\angle AMD).

Fixed, thank you Luis.

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