The area of circle O is added to its diameter. If the circumference of circle O is then subtracted from this total, the result is 12. What is the radius of circle O?
Choose the correct choice from the following.
A) – 2 / pi B) 2 C) 3 D) 4 E) 6

Rationale: pi * r ^ 2 + 2 r - 2 * pi * r = 12 simplifying the equation : pi * r ( r - 2 ) + 2 r = 12 without much algebraic : we can test the answers quickly , then 6 is the only possible answer that will eliminate pi from equation . answer is e
Answer: E