2007 年

$\dfrac{\cos A}{\sin A}+\dfrac{\sin A}{\cos A}=$

Solve the equation $\sin\theta=\sqrt{3}\cos\theta$, where $0^\circ\le\theta\le 90^\circ$.

In the figure, $ABC$ is a right-angled triangle. $BD$ is the angle bisector of $\angle ABC$. If $AB=c$, then $CD=$

In the figure, $ABCDE$ is a right pyramid with the square base $BCDE$. $F$ is a point lying on $AC$ such that $BF$ and $DF$ are perpendicular to $AC$. The angle between the plane $ABC$ and the plane $ACD$ is

Which of the following plane figures have rotational symmetry?

In the figure, the square $ABCD$ is divided into nine identical squares and four of them are shaded. The number of axes of reflectional symmetry of the square $ABCD$ is

If the sum of the interior angles of a convex $n$-sided polygon is $4$ times the sum of the exterior angles of the polygon, then $n=$

In the figure, $AY$ and $CY$ are the angle bisectors of $\angle BAX$ and $\angle DCX$ respectively. If $\angle AXC=100^\circ$, then $\angle AYC=$

If the point $(3,-2)$ is rotated clockwise about the origin through $90^\circ$, then the coordinates of its image are

If the rectangular coordinates of the point $A$ are $(-1,1)$, then the polar coordinates of $A$ are