Question

the diameter of a circle is 22cm. what is the area of the circle?

Explanation:

Step1: Find the radius

The radius $r$ of a circle is half of the diameter $d$. Given $d = 22$ cm, so $r=\frac{d}{2}=\frac{22}{2}=11$ cm.

Step2: Calculate the area

The area formula of a circle is $A=\pi r^{2}$. Substitute $r = 11$ cm into the formula, we get $A=\pi\times11^{2}=121\pi$ $cm^{2}$. Taking $\pi\approx3.14$, then $A\approx121\times3.14 = 379.94$ $cm^{2}$.

Answer:

$121\pi$ $cm^{2}$ (or approximately $379.94$ $cm^{2}$)