Cho hình vẽ dưới đây, tính giá trị của $x$ ?

$\Delta BDC$

$\Delta CBD$

$\Delta BCD$

$\Delta DCB$

$\Delta EDA \backsim \Delta ABC$

$\Delta ADE \backsim \Delta ABC$          

$\Delta AED \backsim \Delta ABC$          

$\Delta DEA \backsim \Delta ABC$

$10\,cm$        

$12\,cm$        

$15\,cm$        

$9\,cm$

$\Delta BDC$

$\Delta CBD$

$\Delta BCD$

$\Delta DCB$

$\Delta BDC$

$\Delta CBD$

$\Delta BCD$

$\Delta DCB$

$\widehat {ABE} = \widehat {ACD}$

$AE.CD = AD.BC$

$AE.CD = AD.BE$  

$AE.AC = AD.AB$

$\Delta EDA \backsim \Delta ABC$

$\Delta ADE \backsim \Delta ABC$          

$\Delta AED \backsim \Delta ABC$          

$\Delta DEA \backsim \Delta ABC$