Question

What will be the diameter of a semi-circle
whose area is 308 cm2
a. 22 cm
b. 28 cm
c. 7 cm
d. 14 cm​

Answer 1

Answer:

28cm

Option b

Step-by-step explanation:

$area \: of \: semicircle \: = \frac{ \pi {r}^{2}}{2}$

$308 = \frac{22}{7} \times \frac{ {r}^{2}}{2}$

$\frac{308 \times 7 \times 2}{22} = {r}^{2}$

$\frac{4312}{22} = {r}^{2}$

${r}^{2} = 196$

$r = \sqrt{196}$

$r = 14cm$

diameter= 2 x r

= 2 x 14

= 28cm

Answer 2

Answer:

b. 28 cm

Step-by-step explanation:

$\pi {r}^{2} \div 2 = 308cm^{2}$

So, bringing 2 and pi to other side, multiplying 308 times 2 and divide resultant by

${r}^{2} =( 308 \times 2) \div \pi$

After calculation answer will be

${r}^{2} = 196.0788 \: {cm}^{2}$

So radius if the given circle is

$r = \sqrt{196.078} {cm}^{2} \\ r = 14.00288 \: cm$

We know that Diameter is twice radius. So,

$d = r \times 2 \\ d = 14 cm\times 2 \\ d = 28 \: cm \: ( appox)$