2004 年

In the figure, $TS$, $SQ$ and $QP$ are tangents to the circle at $T$, $R$ and $P$ respectively. If $TS /\!/ PQ$, $TS=3$ and $QP=12$, then the radius of the circle is

If the straight line $x+y-3=0$ divides the circle $x^2+y^2+2x-ky-4=0$ into two equal parts, then $k=$

The equation of a circle is $x^2+y^2-4x+2y+1=0$. Which of the following is/are true? I. The circle touches the $y$-axis. II. The origin lies outside the circle. III. The centre of the circle lies in the second quadrant.

The mean deviation of the four numbers $x-8$, $x-2$, $x+3$ and $x+7$ is