Question

The diameter of a circle is 18 cm. What is its are in terms of π.a. 324 π cm^2b. 180 π cm^2c. 81 π cm^2d. 18 π cm^2

Answer 1

Explanation

The formula to calculate the area of a circle is:

$\begin{gathered} A=\pi r^2 \\ \text{ Where} \\ A\text{ is the area} \\ r\text{ is the radius} \end{gathered}$

So, we have:

$r=\frac{\text{ diameter}}{2}=\frac{18cm}{2}=9cm$$\begin{gathered} A=\pi r^{2} \\ A=\pi(9cm)^2 \\ A=81\pi cm^2 \end{gathered}$Answer

81π cm²