1985 年

In the figure, $ABCD$ is a cyclic quadrilateral. $BA$ is produced to $E$. $DA$ bisects $\angle CAE$. $\angle BCD=$

The exterior angles of a pentagon are $x^\circ$, $2x^\circ$, $3x^\circ$, $4x^\circ$, $5x^\circ$. The smallest interior angle of the pentagon is

In the figure, $A$, $D$, $E$ and $B$ lie on a straight line. $CE$ bisects $\angle ACB$ and $CD\perp AB$. $\angle DCE=$

In the figure, $ABCD$ is a rhombus. $B$ is the centre of the circle. $\angle ABC=$

The distance between $(1-k,\ k)$ and $(2,\ 1+k)$ is $\sqrt{26}$, $k=$

The equation of the perpendicular bisector of the line joining $(1,\ 2)$ and $(7,\ 4)$ is

In the figure, the circle passes through $(0,\ 0)$ and cuts the two axes at $(6,\ 0)$ and $(0,\ -8)$. Its equation is

The equation of a circle is $x^2+y^2-4x-5=0$. Which of the following is/are true?

I. The circle passes through the origin. II. The centre lies on the $x$-axis. III. The line $x-5=0$ touches the circle.

The mean of the above distribution is

There are four balls, numbered 1, 2, 5 and 10 in a bag. If 2 balls are taken out at random, the probability that the sum of the numbers on the two balls drawn is greater than or equal to 7 is