In the following figure,find the radius of the circle.

$\overrightarrow{ PA }$ and $\overrightarrow{ PB }$ are tangents to $\odot( O , 5) .$ If $OP = 13,$ then $PB = \ldots \ldots \ldots \ldots$

Point $P$ lies in the exterior of a circle with centre $O$. $OP = 34$ and a tangent through $P$ touches the circle at $Q$. If $PQ = 16$,then find the diameter of the circle.

As shown in the figure,$\overleftrightarrow{AB}$,$\overleftrightarrow{AC}$ and $\overleftrightarrow{PQ}$ are the tangents to $\odot(O, r)$. Then the perimeter of $\Delta APQ = \ldots$

In the following figure,if $AB = 10$,then $AC = \ldots$

Write 'True' or 'False' and give reasons for your answer.
In the figure,$PQL$ and $PRM$ are tangents to the circle with center $O$ at the points $Q$ and $R$ respectively,and $S$ is a point on the circle such that $\angle SQL = 50^{\circ}$ and $\angle SRM = 60^{\circ}$. Then $\angle QSR$ is equal to $40^{\circ}$.