The angle subtended by the chord $x+y-1=0$ of the circle $x^2+y^2-2 x+4 y+4=0$ at the origin is

Let $P$ be any point on the circle $x^2+y^2=25$. Let $L$ be the chord of contact of $P$ with respect to the circle $x^2+y^2=9$. The locus of the poles of the lines $L$ with respect to the circle $x^2+y^2=36$ is

If the circles $S \equiv x^2+y^2-14 x+6 y+33=0$ and $S^1 \equiv x^2+y^2-a^2=0(a \in N)$ have 4 common tangents, then possible number of values of $a$ is

If the area of the circum-circle of triangle formed by the line $2 x+5 y+\alpha=0$ and the positive coordinate axes is $\frac{29 \pi}{4} S q$, units, then $|\alpha|=$