math (algebra honors) #2
posted by K.S. on .
If the radius of a circle is increased by 6 cm, the new area is 121 (pi) cm^2. Find the radius of the original border using factoring.

the answer is 5 by common sense, i would reevaluate your schools "honours" program
the area of a circle is pi(r^2)
therefore pi(x+6)^2=121pi
now just solve
(x+6)^2=121
x+6=11
x=5