The equation of straight line which passes through the point $$\left(a \cos ^3 \theta, a \sin ^3 \theta\right)$$ and perpendicular to $$x \sec \theta+y \operatorname{cosec} \theta=a$$ is

The two lines $$l x+m y=n$$ and $$l^{\prime} x+m^{\prime} y=n^{\prime}$$ are perpendicular if

A line cuts off equal intercepts on the co-ordinate axes. The angle made by this line with the positive direction of $$X$$-axis is