In parallelogram $PQRS$,$PQ = 8 \, \text{cm}$ and $QR = 5 \, \text{cm}$,then the perimeter of $PQRS = \ldots \ldots \ldots$ (in $, \text{cm}$)

All the angles of a quadrilateral are equal. What special name is given to this quadrilateral?

In the figure,$P$ is the mid-point of side $BC$ of a parallelogram $ABCD$ such that $\angle BAP = \angle DAP.$ Prove that $AD = 2 CD.$

In a parallelogram $ABCD$,$AB = 10 \, cm$ and $AD = 6 \, cm$. The bisector of $\angle A$ meets $DC$ in $E$. $AE$ and $BC$ produced meet at $F$. Find the length of $CF$ (in $cm$).

$D, E$ and $F$ are the mid-points of the sides $BC, CA$ and $AB$ respectively of an equilateral triangle $ABC$. Show that $\triangle DEF$ is also an equilateral triangle.

Perimeter of rectangle $PQRS$ is $40\, cm$. If $PQ : QR = 3 : 5$,then $RS = \ldots \ldots \ldots \, cm$.