1995 AHSME Problem 19

Equilateral triangle DEF is inscribed in equilateral triangle ABC such that \overline{DE} \perp \overline{BC}. The ratio of the area of \triangle DEF to the area of \triangle ABC is \mathrm{(A) \ \frac {1}{6} } \qquad \mathrm{(B) \ \frac {1}{4} } \qquad \mathrm{(C) \ \frac {1}{3} } \qquad \mathrm{(D) \ \frac {2}{5} } \qquad \mathrm{(E) \ \frac {1}{2} }

Full credit goes to MAA for authoring these problems. These problems were taken on the AOPS website.