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 10. What is the radius of circle O?  Choose the correct choice from the following options
A) –2/pi
B) 2
C) 3
D) 4
E) 5
pi*r^2 + 2r -2*pi*r = 10   Simplifying the equation: pi*r(r-2)+2r=10   Without much algebraic: We can Test the answers quickly, then 5 is the only possible answer that will eliminate pi from equation.   Answer is 5
<result>E</result>
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 10. What is the radius of circle O?