The areas of two concentric circles are 1386 cm2 and 962.5 cm2. The width of the ring is

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KollegeApply · Accepted Answer

3.5 cm Let r cm and R cm be the radii of two concentric circles. Thus, we have: $\pi$R2 = 1386 => $\frac{22}{7}$xx"R"^2 = 1386 `rArr "R" = (1386xx7/22) "cm"^2` $\Rightarrow$ R2 = 441 cm2 $\Rightarrow$ R = 21 cm Also, $\pi$r2 = 962.2 => $\frac{22}{7}$xx"r"^2 = 962.2 $\Rightarrow$ r2 = (962.2 $\times$ $\frac{7}{22}$) "cm"^2 `=> "r"^2 = (962.$\frac{2}{10}$xx7/22)"cm"^2 =>"r"^2 =$\frac{1225}{4}$ "cm"^2 => "r" = $\frac{35}{2}$ "cm"` $\therefore$ Width of the ring = (R - r) = (21 - $\frac{35}{2}$) "cm" = $\frac{7}{2}$ "cm" = 3.5 cm

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