Tangent is drawn to the ellipse $\frac{x^2}{27}+y^2=1$ at $(3 \cdot \sqrt{3} \cos\theta,\sin\theta)$ $[ where \theta \in \left( 0,\frac{\pi}{2}\right)]$. then, the value of $\theta$ such that the sum of intercepts on axes made by this tangent is minimum, is :