SMO 2007 Junior Round 1 Question 30

In $\triangle ABC$, $\angle BAC=45^\circ$. $D$ is a point on $BC$ such that $AD$ is perpendicular to $BC$. If $BD=3$ cm and $DC=2$ cm, and the area of $\triangle ABC$ is $x$ cm$^2$, find the value of $x$.