Question

11. The area of a circle is 314 cm². If π = 3.14, then its diameter is :
(A) 100 cm (B) 50 cm
(C) 20 cm (D) 10 cm

Answer 1

Answer:

20 cm

Step-by-step explanation:

Area of circle = πr^2

Here, let the radius be r.

= > area = πr^2

= > 314 = πr^2

= > 314/π = r^2

= > 314/3.14 = r^2

= > 100 = r^2

= > 10 = r

Hence,

Diameter = 2 * radius

Diameter = 2*10 cm = 20 cm

Answer 2

Given:

• Area of a circle = 314 cm².
• $\pi \: = 3.14$

To Find:

• The diameter of the circle.

Solution:

Let the radius of the circle be r cm.

Now,

By condition,

$\sf{Area = \pi {r}^{2} }$

$\sf{\implies 314 = 3.14 {r}^{2}}$

$\sf{\implies \frac{314}{3.14} = {r}^{2} }$

$\sf{\implies \frac{\cancel{314} \times 100}{\implies \cancel{314}} = {r}^{2} }$

$\sf{\implies 100 = {r}^{2} }$

$\sf{\implies 10 = r}$

Hence, the radius of the circle is = 10 cm.

Now,

Diameter = 2 × radius

Diameter = 2 × 10

Diameter = 20 cm.

$\rule{300}{2}$