MathDB
Turkey NMO 2006 1st Round - P33 (Geometry)

Source:

February 3, 2013
geometryangle bisector

Problem Statement

Let ABCDABCD be a convex quadrileteral such that m(ABD^)=40m(\widehat{ABD})=40^\circ, m(DBC^)=70m(\widehat{DBC})=70^\circ, m(BDA^)=80m(\widehat{BDA})=80^\circ, and m(BDC^)=50m(\widehat{BDC})=50^\circ. What is m(CAD^)m(\widehat{CAD})?
<spanclass=latexbold>(A)</span> 25<spanclass=latexbold>(B)</span> 30<spanclass=latexbold>(C)</span> 35<spanclass=latexbold>(D)</span> 38<spanclass=latexbold>(E)</span> 40 <span class='latex-bold'>(A)</span>\ 25^\circ \qquad<span class='latex-bold'>(B)</span>\ 30^\circ \qquad<span class='latex-bold'>(C)</span>\ 35^\circ \qquad<span class='latex-bold'>(D)</span>\ 38^\circ \qquad<span class='latex-bold'>(E)</span>\ 40^\circ