The sector of a circle has perimeter of 144 cm and central angle 180o. Find its radius?	Choose the correct choice from the following options.
A) 25 cm B) 32 cm C) 14 cm D) 28 cm E) 21 cm

Rationale: "let the radius is x cm perimeter of the sector = length of the arc + 2 ( radius ) 144 = ( 180 / 360 * 2 * 22 / 7 * x ) + 2 ( x ) 144 = 22 x / 7 + 2 x 144 = 36 x / 7 36 x = 1008 x = 28 answer : d"
Answer: D