Question

Find the area of a circle with the diameter of 3 centimeters. Use 3.14 for pi

Answer 1

The equation for the area of circle is:
$A = \pi r^{2}$
where r = radius.

The radius of a circle is 1/2 its diameter. Since you know the diameter is 3cm, its radius must be 3cm/2 = 1.5cm. 

Now just plug r=1.5 into the equation for the area of the circle to find the area:
$A = \pi r^{2}$
$A = \pi (1.5)^{2}$
$A = 7.07 cm^{2}$