[填空题]
The following diagram shows hh c,7-zn9dv-f xszhk q5b7*striangle A B C . Point o r ca9u:f 6uv4df7xo3D lies on [A C] so that [DB] bisects CEr3 c9vd74a xfufoo6:u AA. The area of the triangle A B C is 3$ \mathrm{~cm}^{2}$ .
$\mathrm{AB}=2 \sqrt{7} \mathrm{~cm}, \mathrm{BC}=x \mathrm{~cm}$ , and $\mathrm{CBD}=\theta$ , where $ \sin \theta=\frac{3}{4} $ Find the value of x in the form of $ \frac{a}{b}$ where a and b are positive integers. x =
