
$\begin{aligned}
& \text { Area of } \triangle \mathrm{AOB}=\frac{1}{2} \
& \text { Area of } \triangle \mathrm{AMN}=\frac{4}{9} \times \frac{1}{2}=\frac{2}{9}
\end{aligned}EquationofABis\mathrm{x}+\mathrm{y}=1\begin{aligned}
& \mathrm{OA}=1, \mathrm{AM}=\sec \left(45^{\circ}-\theta\right) \
& \mathrm{AN}=\sec \left(45^{\circ}-\theta\right) \cos \theta \
& \mathrm{MN}=\sec \left(45^{\circ}-\theta\right) \sin \theta
\end{aligned}\begin{aligned} & \operatorname{Ar}(\triangle \mathrm{AMN})=\frac{1}{2} \times \sec ^2\left(45^{\circ}-\theta\right) \sin \theta \cdot \cos \theta=\frac{2}{9} \ & \Rightarrow \tan \theta=2, \frac{1}{2} \ & \tan \theta=2 \text { is rejected } \ & \frac{\mathrm{AN}}{\mathrm{NB}}=\frac{\lambda}{1}=\cot \theta=2\end{aligned}$