In $\Delta ABC$,$P$ and $Q$ are the midpoints of $AB$ and $AC$ respectively. If $BC = 8.2 \text{ cm}$,then $PQ = \dots \text{ cm}$.

Angles of a quadrilateral are in the ratio $3:4:4:7$. Find all the angles of the quadrilateral.

Through $A, B$ and $C$,lines $RQ, PR$ and $QP$ have been drawn,respectively parallel to sides $BC, CA$ and $AB$ of a $\triangle ABC$ as shown in the figure. Show that $BC = \frac{1}{2} QR$.

In quadrilateral $ABCD$,the angles are in the ratio $\angle A : \angle B : \angle C : \angle D = 2 : 4 : 5 : 7$. Find the measure of each angle of the quadrilateral and state the type of quadrilateral $ABCD$.

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

$(1)$ If no three points out of four coplanar points are collinear,then a $\ldots \ldots \ldots$ figure formed by joining these four points in order is called a quadrilateral.
$(2)$ $A$ quadrilateral has $\ldots \ldots \ldots$ pairs of opposite sides.