Question

Find the area of a circle whose diameter is 18 cm. (round to nearest whole cm.2)

Select one:

a.
321 cm.2


b.
201 cm.2


c.
254 cm.2


d.
98 cm.2

Answer 1

• Option c. 254 cm²

⠀

Given :

• Find the area of a circle whose diameter is 18 cm.

We know,

`{ \longrightarrow\qquad \bf{Area_((Circle) )= \pi {r}^(2) }}`

⠀

Where,

• r is the radius of the circle. As Diameter is 18 cm, Therefore, The radius will be 9 cm

• We will take the value of π as
  `\sf \: (22)/(7)`

⠀

Now, Substituting the values in the formula :

`{\longrightarrow\qquad \sf{Area_((Circle) )= (22)/(7) * {9}^(2) }}`

⠀

`{\longrightarrow\qquad \sf{Area_((Circle) )= (22)/(7) * 81 }}`

⠀

`{\longrightarrow\qquad \sf{Area_((Circle) )= \frac{22 } { \cancel7} * \cancel{81} }}`

⠀

`{\longrightarrow\qquad \sf{Area_((Circle) )\approx {22 *11.57 } }}`

⠀

`{\longrightarrow\qquad \bf{Area_((Circle) )\approx 254.57 }}`

⠀

Therefore,

• Area of the circle is 254 cm². (Nearest whole cm²).

Answer 2

Diameter of circle is 18 cm.

Therefore,

Radius = 18/2

Radius = 9 cm

We have been asked to determine the area of Circle .

Formula Used

`☯ \bf \:Area \: of \: circle \: = \pi {r}^(2)`

Putting the value we obtain

`\implies\sf \: Area \: of \: circle \: = (22)/(7) * {9}^(2) \\ \\ \implies\sf \: Area \: of \: circle \: = (22)/(7) * 81 \\ \\ \implies\sf \: Area \: of \: circle \: = (22 * 81)/(7) \\ \\ \implies\sf \: Area \: of \: circle \: = (1782)/(7) \\ \\ \implies\sf \: Area \: of \: circle \: = 254.57 \: {cm}^(2) \\ \\ \implies\sf \: Area \: of \: circle \: = 254 {cm}^(2)`

So, the area of the circle is 254 cm² (nearest whole cm²)

Option (c) 254cm² is your answer.