MathDB

1

Part of 2009 National Olympiad First Round

Problems(1)

Interior point

Source: 0

4/28/2009
ABCD ABCD is a square. Let E E be a point on the segment BC BC and F F be a point on the segment ED ED. If DF \equal{} BF and EF \equal{} BE, then ∠DFA \angle DFA is
<spanclass=′latex−bold′>(A)</span> 45∘<spanclass=′latex−bold′>(B)</span> 60∘<spanclass=′latex−bold′>(C)</span> 75∘<spanclass=′latex−bold′>(D)</span> 80∘<spanclass=′latex−bold′>(E)</span> 85∘<span class='latex-bold'>(A)</span>\ 45^\circ \qquad<span class='latex-bold'>(B)</span>\ 60^\circ \qquad<span class='latex-bold'>(C)</span>\ 75^\circ \qquad<span class='latex-bold'>(D)</span>\ 80^\circ \qquad<span class='latex-bold'>(E)</span>\ 85^\circ