Junior Mathematical Olympiad 2007 Q14

[JMO 2007 B2 Edited] The diagram shows a quadrilateral $ABCD$ in which $AB$, $BC$ and $AD$ are all of length 1 unit, $\angle BAD$ is a right angle and $\angle ABC$ is $60^{\circ}$. Determine the angles $\angle DBC$ and $\angle BDC$.