Question

Find the radius of a circle with the area 49mm

Answer 1

$\bold \red{ area \: of \: circle = \pi \times r {}^{2} } \\ \bold \red{where \: } \\ \bold \red{\pi = \frac{22}{7} \: or \: 3.14159 \: (approx)} \\ \bold \red{r = radius \: of \: circle}$

$49 = \pi {r}^{2} \\ {r}^{2} = \frac{49}{\pi} = \frac{49}{ \frac{22}{7} } = \frac{49}{22} \times 7 \\ r = 4(approx)$