Question

find the radius of a circle whose area is 77cm​

Answer 1

Given,

area=77cm

Implies that,

π*r*r=77

r*r=77/π

but, π=22/7

r*r=77/(22/7)

=(77*7)/22

=(7*7)/2

r^2=(7*7)/2

r=√[(7*7)/2]

Therefore,

r=7√2

Answer 2

$\red {\huge {\underline{ \frak{Your \: answEr : }}}}$

$\pink{\large{\boxed{ \bold{ Area \: of \: Circle = \pi {r}^{2} }}}}$

$\blacksquare$ Value of π = $\large\frac{22}{7}$

$\large\longrightarrow \bold{Area = \frac{22}{7} \times {r}^{2} }$

$\large\longrightarrow \bold{77 =\frac{22}{7} \times {r}^{2} }$

$\large\longrightarrow \bold{ {r}^{2} = \frac{(77 \times 7)}{22} }$

$\large\longrightarrow \bold{r = \sqrt{ \frac{7 \times 7}{2} } }$

$\purple{ \huge\longrightarrow \boxed{\bold{r = \frac{7}{ \sqrt{2} } \: cm }}}$

$\huge{\red{\ddot{\smile}}}$