What is the area of a circle

To calculate the area of a circle, we have this formula:

Let's do an example: Calculate the are of a circle whose diameter is 20 cm.

First, we need to get the radius of the circle. WWe should know the diameter of a circle is equal to , so the radius is half of the diameter.

If the diameter is 20 cm, then the radius is 10 cm.

Now we have the radius and teh formula , so we can calculate:

= 314.16

a reflection across the x-axis , followed by the by a reflection across the y-axis , and then a scale dilation of 0.5 .