Question
Mon March 04, 2013 By:

# on increasing the diameter of a circle by 40% its area will be increased by?

Mon March 04, 2013
If the diameter of a circle is increased by 40%, then the new diameter would be
d' = d + 40% d
i.e. d' = 1.4d

Area of a circle (A) = pi*r2 = pi*d2/4
So, the area of new circle (A') = pi*(1.4d)2/4 = 1.96 *pi*d2/4 = 1.96A

% increase in area = (A'-A)/A * 100 = (1.96A -A)/A * 100 = 96%
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