1983 年

In the figure, all the corners are right-angled. If the perimeter of the figure is $40$, then $x=$

If the lengths of the diagonals of a rhombus are $2\text{ cm}$ and $4\text{ cm}$ respectively, what is the area of the rhombus?

A hollow cylindrical metal pipe, $1\text{ m}$ long, has an external radius and an internal radius of $5\text{ cm}$ and $4\text{ cm}$ respectively. The volume of metal is

Two men cycle round a circular track which is $3\text{ km}$ long. If they start at the same time and at the same spot but go in opposite directions with speeds $6\text{ km/h}$ and $9\text{ km/h}$ respectively, for how long must they cycle before they meet for the first time?

A man marks his goods at a price that will bring him a profit of $25\%$ on the cost price. If he wants to sell his goods to a friend at the cost price, the percentage discount on the marked price should be

In the figure, $AB=p$, $DC=q$ and $\angle A=\angle D=90^\circ$. $BC=$

In the figure, $\angle ABC=\angle ACD=\angle BDC=90^\circ$. $AC=a$. $CD=$

In the figure, $OAB$ is a sector of a circle. Radius $OA$ is $3\text{ cm}$ long and arc $AB=2\text{ cm}$. The area of the sector is

In the figure, $D$ is a point on $BC$ and $AC=AD=BD$. $\angle CAD=$

The sum of the six marked angles in the figure is