The Radius of the Circle in the Figure Is 2 $D C$

The radius of the circle in the figure is 2 units. Express the length $D C$ in terms of $\alpha$ .

A) $2 \cos \alpha$
B) $2 \cot \alpha$
C) $2 \sin \alpha$
D) $2 \tan \alpha$
E) $2 \sec \alpha$