The perimeter of a certain sector of a circle is equal to half that...

The perimeter of a certain sector of a circle is equal to half that of the circle of which it is a sector. The circular measure
\( \mathrm{P} \) of one angle of the sector is

W)
(a) \( (\pi-2) \) radian
(b) \( (\pi+2) \) radian
(c) \( \pi \) radian
(d) \( (\pi-3) \) radian