Question 125
The diagonals $AC$ and $BD$ of the quadrangle $ABCD$ intersect at the point $O$. It is known that the diagonal $BD$ is perpendicular to the side $AD$, $\angle BAD = \angle BCD = 60^\circ$, and $\angle ADC = 135^\circ$. Find the ratio $DO:OB$.
Figure 1
Figure 1