Question 1145527
.
<pre>

{{{pi*r^2 - pi*(r-10)^2}}} = 4710


r^2 - (r-10)^2 = 4710/3.14

r^2 - r^2 + 2r - 100 = 4710/3.14


2r = 4710/3.14 + 100


r = {{{(1/2)*(4710/3.14+100)}}} = 800 cm = 8 meters.    <U>ANSWER</U>
</pre>