The equation $x^2 + y^2 - 2x - 4y +5 = 0$ represents

The curve represented by the equation $\dfrac{x^{2}}{\sin \sqrt{2}-\sin \sqrt{3}}+\dfrac{y^{2}}{\cos \sqrt{2}-\cos \sqrt{3}}=1$ is

A circle of non-zero radius has origin as its centre. If it passes through the point of intersection of two curves $y^2 = 4ax$ and $x^2 = 4ay$, then its equation is