其他

In the figure, $ABCD$ is a square. Arcs $AC$ and $BD$ are drawn with centres $D$ and $C$ respectively, intersecting at $O$. Arc $AO$ : Arc $OC=$

In the figure, $ABCD$ and $EFGH$ are two squares of side $1$. They are placed one upon the other with their centres both at $O$ to form a star with $16$ sides, each of length $x$. Find $x$.

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 $MBND$. $h=$