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Turkey NMO 2006 1st Round - P17 (Geometry)

Source:

February 2, 2013
geometrytrigonometry

Problem Statement

Let DD be a point on the side [BC][BC] of ABC\triangle ABC such that BD=2|BD|=2 and DC=6|DC|=6. If AB=4|AB|=4 and m(ACB^)=20m(\widehat{ACB})=20^\circ, then what is m(BAD^)m(\widehat {BAD})?
<spanclass=latexbold>(A)</span> 10<spanclass=latexbold>(B)</span> 18<spanclass=latexbold>(C)</span> 20<spanclass=latexbold>(D)</span> 22<spanclass=latexbold>(E)</span> 25 <span class='latex-bold'>(A)</span>\ 10^\circ \qquad<span class='latex-bold'>(B)</span>\ 18^\circ \qquad<span class='latex-bold'>(C)</span>\ 20^\circ \qquad<span class='latex-bold'>(D)</span>\ 22^\circ \qquad<span class='latex-bold'>(E)</span>\ 25^\circ