Answer:
See Explanation
Step-by-step explanation:
[tex] m\angle BOC= 120\degree.... (Given) [/tex]
Since, measure of minor arc is equal to the measure of the central angle.
[tex] \therefore m\widehat {BC} = m\angle BOC\\\\
\therefore m\widehat {BC} =120\degree \\\\
\because m\angle PBC = \frac{1}{2} \times m\widehat {BC}\\(By\: tangent\: secant\: theorem) \\
\huge\purple{\boxed {\therefore m\angle PBC =60\degree}} \\\\[/tex]
Since, AC is the diameter of the circle.
[tex] \therefore m\widehat {AB} +m\widehat {BC} = 180\degree \\\\
\therefore m\widehat {AB} +120\degree = 180\degree \\\\
\therefore m\widehat {AB} = 180\degree - 120\degree\\\\
\huge\orange {\boxed {\therefore m\widehat {AB} = 60\degree}} [/tex]
