Suppose in the figure below, $AD\ \text{//} \ BC$, $BD=BC$, $CD=CE$, 
 and $ABCD$ is a trapezoid; $\measuredangle ABD=15°$

Prove that: $\triangle BAC$ is a right-angled isosceles triangle. 

[![enter image description here](https://i.stack.imgur.com/XOg8Y.png)](https://i.stack.imgur.com/XOg8Y.png)