Question

The area of a circle, in terms of
π
, is 80
π
m2.
Find the value of the radius.
Give your answer as a simplified surd

Answer 1

$we \: know \: that \: \\ area \: of \: circle \: is\ \: \pi \times {r}^{2} < ........ |1| \\ but \: \: given \: that \: \: \\ area \: of \: circle \: is \: 80\pi \: ....... |2| \\ from \: 1and \: 2 \\ \\ \pi \times {r}^{2} = 80\pi \\ {r}^{2} = 80 \\ r = \sqrt{80} = 8.9$