The common point of tangent line and circle is known as point of . 

Given : Point $O$ is the centre of a circle. $MA$ and $MB$ are two tangent segments drawn from an external point $M$ to the circle at $A$ and $B$ respectively. Prove that: $MA=MB$

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.