Area of Circles

The area of a circle depends only on its radius: \(A = \pi r^2\). This NSW Year 8 maths subtopic (NESA outcome MA4‑ARE‑C‑01) shows where the formula comes from and uses it with a given radius or diameter, giving answers in terms of \(\pi\) or rounded with the \(\pi\) key.

You will find the area of a ring such as a washer, the region left when a circle is cut from a rectangle, and a radius or diameter from a given area or circumference. You will also see why doubling the radius makes the area four times as large, decide whether one large pizza beats two smaller ones, and find how much of a lawn a sprinkler misses. It is part of Year 8 Area and Perimeter.