if radius of a circle is reduced by 10%,then how much % of its area will be reduced?
Choose the most appropriate option
A) 10%  B) 19%  C) 20%  D) 36%  E) 30%
let initial radius=a then,area=πa^2.   new radius=90% of a=9a/10.new area=π*81a^2/100=81/100πa^2   reduce in area=[πa^2-81/100πa^2]=19/100πa^2   % reduce=[(19*πa^2/100)*(1*100/πa^2)]%=19%   answer 19%
<result>B</result>
if radius of a circle is reduced by 10%,then how much % of its area will be reduced?