How do I find the area of a circle C with diameter 14cm?

The formula for the area of a circle is π r². To use this formula we first need to find r, the radius of the circle. The radius is the distance from the centre of the circle to the edge, and is equal to half of the diameter. The radius of this circle is half of 14, or 14/2 = 7. Now we can use the formula for area.  π x 7² = π x 49 = 153.938..... or 159.3 to 1 decimal place. It is important not to forget units with your final answer if they are given in the question, so the area of our circle C = 159.3 cm².