A line intersecting a circle in two points is called a .

What is the circumference of the largest circle which can be inscribed in a square of side $14 cm$? ($\mathrm{\pi }=\frac{22}{7}$)

In the given figure $TP$ and $TQ$ are two tangents to the circle with centre $O$, touching at $A$ and $C$ respectively. If $\angle BCQ=55°$ and $\angle BAP=60°$, find $\angle OBA$ and $\angle OBC$

In the given figure $TP \& TQ$ are two tangents to the circle with centre $O$, touching at $A \& C$ respectively. If $\angle BCQ=55° \& \angle BAP=60°$, find $\angle ATC$ in degrees.