We know that the value of an interior angle of a regular 𝑛-sided polygon =n−2n×180°
⇒165°=n−2n×180°⇒11=n−2n×12⇒11n=12n−24⇒11n−12n=−24⇒−n=−24⇒n=24
The value of an exterior angle of a regular 𝑛−sided polygon =360°n
The value of an exterior angle of 24-sided polygon =360°24=15°