http://img116.imageshack.us/img116/8376/mathsch6.jpg

The answer is approximately 2.29

I attempted to use sine law in order to find DN and my answer was close

$\displaystyle \frac{sin70}{6}=\frac{sin20}{DN}$

$\displaystyle \frac{sin70}{6}=0.157$

$\displaystyle \frac{sin20}{0.157}=DN=2.18$

Is there another method of solving this problem?