Question

the diameter of a circle is 21 cm. find its area to the nearest whole number.

Explanation:

Step1: Find the radius

The radius \(r\) of a circle is half of the diameter \(d\). Given \(d = 21\) cm, so \(r=\frac{d}{2}=\frac{21}{2}=10.5\) cm.

Step2: Use the area formula

The area formula of a circle is \(A=\pi r^{2}\). Substitute \(r = 10.5\) into the formula: \(A=\pi\times(10.5)^{2}\).

$$
LATEXBLOCK0
$$

Step3: Round to the nearest whole number

Rounding \(346.185\) to the nearest whole number. Since the decimal part \(0.185\lt0.5\), we get \(346\).

Answer:

\(346\)