Question 108

If the radius of a circle is increased by 10%, then the percent increase in its area is

Solution

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let the radius of the circle is r then area = $$\pi$$ $$r^{2}$$ 

then in given in the question the new radius is = 1.1r 

then the new area  = $$\pi$$ $$(1.1r)^{2}$$

                             = 1.21$$\pi$$ $$r^{2}$$

then the % change in area = (1.21$$\pi$$ $$r^{2}$$ - $$\pi$$ $$r^{2}$$)\$$\pi$$ $$r^{2}$$ $$\times$$100

then the % change in area = 21%   Answer 

                                      

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