Question

A circular disc has a diameter of 24 centi-meters. What is the area of the disc?

Answer 1

Hint: Here in this question, we have to find the area of the disc. A disk is a round, flat circle. For this we have to consider the formula of area of circle $$A=\pi r^2$$, where ‘$$r$$’ be the radius of circle which equals half of the diameter then on substituting the values in formula and on further simplification we get the required solution.

Complete step by step answer:
Given the circular disc of diameter 24 cm, we need to find its area.

Consider the formula of area of circle:
$$\Rightarrow A=\pi r^2$$ ----- (1)
‘$$r$$’ be the radius of circular disc which equal to half of its diameter i.e., $$r={\displaystyle \frac{d}{2}}\Rightarrow {\displaystyle \frac{24}{2}}=12$$cm.
Substitute the value of $$r$$in equation (1), then we have
 $$\Rightarrow A=\pi {\left(12\right)}^2$$
On simplification we get
$$\therefore A=144\pi$$$$c{m}^2$$.
Or
$$\Rightarrow A=144\left(3.14\right)$$
($$\because$$ The value of $$\pi ={\displaystyle \frac{22}{7}}=3.14$$)
$$\therefore A=452.16$$$$c{m}^2$$.
Hence, the area of the circular disc is $$144\pi$$or $$452.16$$$$c{m}^2$$.

Note:
If the diameter of the circle is known to us, we can calculate the radius of the circle, such as $$r={\displaystyle \frac{d}{2}}$$. In mensuration problems, don't forget to write the units. The unit of area is the square unit, such as $$m^2$$, $$c{m}^2$$, etc. Sometimes students get confused between the formula of perimeter and area of circle so for that just check the units like what unit we will get from the formula.