面積與體積

In the figure, $O$ is the centre of the circle. $B$ and $C$ are points lying on the circle. If $OC=2\text{ cm}$ and $OA=1\text{ cm}$, then the area of the shaded region $OABC$ is

In the figure, sector $OXY$ is a thin metal sheet. By joining $OX$ and $OY$ together, which of the following right circular cones can be folded?

If the length of a side of a regular tetrahedron is $3\text{ cm}$, then the height of the tetrahedron is

In the figure, $ABCD$ is a rhombus and $CDE$ is an equilateral triangle. If $ADE$ is a straight line, then the area of the quadrilateral $ABCE$ is

The figure shows a solid right circular cone of height $5\text{ cm}$ and slant height $13\text{ cm}$. Find the total surface area of the cone.

The figure shows a right triangular prism. Find the volume of the prism.

In the figure, $OAB$ is a sector of radius $2\text{ cm}$. If the length of $\widehat{AB}$ is $3\pi\text{ cm}$, then the area of the sector $OAB$ is

If the area of a regular 10-sided polygon is $123\text{ cm}^2$, find the length of the side of the 10-sided polygon. Give the answer correct to the nearest $0.1\text{ cm}$.

In the figure, $OAB$ is a sector. The perimeter and the area of the sector are $x\text{ cm}$ and $y\text{ cm}^2$ respectively. If $x=y$, then $\widehat{AB}=$

The length of a side of a regular 8-sided polygon is $6\text{ cm}$. Find its area, correct to 3 significant figures.