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P17 [Geometry] - Turkish NMO 1st Round - 2002

Source:

August 8, 2014
geometrytrapezoidincentersymmetry

Problem Statement

Let ABCDABCD be a trapezoid and a tangential quadrilateral such that ADBCAD || BC and AB=CD|AB|=|CD|. The incircle touches [CD][CD] at NN. [AN][AN] and [BN][BN] meet the incircle again at KK and LL, respectively. What is ANAK+BNBL\dfrac {|AN|}{|AK|} + \dfrac {|BN|}{|BL|}?
<spanclass=latexbold>(A)</span> 8<spanclass=latexbold>(B)</span> 9<spanclass=latexbold>(C)</span> 10<spanclass=latexbold>(D)</span> 12<spanclass=latexbold>(E)</span> 16 <span class='latex-bold'>(A)</span>\ 8 \qquad<span class='latex-bold'>(B)</span>\ 9 \qquad<span class='latex-bold'>(C)</span>\ 10 \qquad<span class='latex-bold'>(D)</span>\ 12 \qquad<span class='latex-bold'>(E)</span>\ 16