Question

if radius of circle is 7 +-0.7 cm.find it's area and error in it
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Answer 1

Given ,

Radius of circle (R) = 7 ± 0.7 cm

We know that , area of circle is given by

$\large \sf \fbox{Area = \pi {(r)}^{2} }$

Therefore ,

$\large \sf \fbox{Δ \: A = 2 \times \frac{Δ \: r}{r} }$

Thus ,

$\sf \mapstoΔ \: A =2 \times \frac{0.7}{7} \\ \\\sf \mapsto Δ \: A = \frac{2}{10} \\ \\\sf \mapstoΔ \: A = 0.2$

$\therefore\sf \underline{The \: error \: in \: area \: will \: be \: ± \: 0.2 }$