Question

what is the area of a circular region whose diameter is 6 centimeters?
a 6π cm
b 9π cm
c 12π square cm
d 9π square cm

Explanation:

Step1: Find the radius

The radius $r$ of a circle is half of the diameter $d$. Given $d = 6$ cm, so $r=\frac{d}{2}=\frac{6}{2}=3$ cm.

Step2: Use the area formula

The area formula of a circle is $A=\pi r^{2}$. Substitute $r = 3$ cm into the formula, we get $A=\pi\times3^{2}=9\pi$ square cm.

Answer:

D. $9\pi$ square cm