In parallelogram $ABCD$,$AB = 12.5 \, cm$ and $BC = 7 \, cm$,then find the perimeter of $ABCD$ in $cm$.

$(1)$ $A$ quadrilateral has ......... pairs of consecutive angles.
$(2)$ The sum of measures of all the four angles of a quadrilateral is ...........

Three angles of a quadrilateral are $75^{\circ}, 90^{\circ}$ and $75^{\circ}$. The fourth angle is (in $^{\circ}$)

Diagonals of a parallelogram are perpendicular to each other. Is this statement true? Give reason for your answer.

In $\Delta PQR$,$A$,$B$,and $C$ are the mid-points of $PQ$,$QR$,and $RP$ respectively. If the perimeter of $\Delta ABC$ is $18.6 \, cm$,then the perimeter of $\Delta PQR$ is $\ldots \ldots \ldots cm$.

Opposite angles of a quadrilateral $ABCD$ are equal. If $AB = 4 \, cm$,determine $CD$ (in $cm$).