If $m_1$ and $m_2$ are the slopes of the direct common tangents drawn to the circles $x^2+y^2-2 x-8 y+8=0$ and $x^2+y^2-8 x+15=0$, then $m_1+m_2=$

If the circumcenter of the triangle formed by the points $A(a, 3), B(b, 5)$ and $C(a, b)$ is $(1,1)$, then out of all the possible coordinates of $C$ the sum of the absolute values of the distinct coordinates of $C$ is

The equation of a circle passing through $(-6,3)$ and touching both the coordinates axes is

The area (in sq units) of the triangle formed by the $x$-axis, the tangent and the normal drawn to the circle $x^2+y^2=10 x$ at the point $(9,3)$ is