1982 年

$AB$ and $CD$ are two buildings of heights $h$ and $d$ respectively. The angles of elevation of $C$ from $A$ and $B$ are respectively $\theta$ and $45^\circ$. $d=$

In the figure, $BP$ is a diameter of the circle. The minor arc $AB$ and the radius are of equal length. $\angle APB=$

If $0\le x\le\pi$ and $\sin x\le\cos x$, what is the range of $x$?

In the figure, $ABCD$ is a square of side $2a$. $M$ and $N$ are the mid-points of $AB$ and $CD$ respectively. $h$ is the height of the parallelogram $MBND$. $h=$

In the figure, $O$ is the centre of the circle. $PQ$ is a diameter. Which of the following is/are true? I. $a=b$ II. $c=2a$ III. $c+d=180^\circ$

In the figure, the length of the minor arc $CD$ is half the length of the minor arc $BC$. $\angle ACD=$

In the figure, $TP$ and $TQ$ touch the circle at $P$ and $Q$ respectively. $R$ is the point on $TQ$ produced such that $PR$ passes through the centre $O$ of the circle. $\angle QPR=$