Question

A circle has a radius of 7 cm .find its area.if its area becomes four times the previous area.find the radius of the new circle

Answer 1

$area \: of \: a \: circle = \pi r {}^{2} \\ \frac{22}{7} \times 7 \times 7 \\ 22 \times 7 \\ 154 \: cm {}^{2} \\ if \: the \: area \: becomes \: four \: time \\ 154 \times 4 \\ 616cm {}^{2} \\ \pi \: r {}^{2} = 616 \\ \frac{22}{7} \times r {}^{2} = 616 \\ r {}^{2} = 616 \times \frac{7}{22} \\ r {}^{2} = 196 \\ r = \sqrt{196} \\ r = 14 \: cm$

Answer 2

Answer:

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