They then apply this knowledge to working out the perimeter of a rectangle and a square. Zach then displays his favourite window, which is a composite rectilinear shape. The children talk through ...

The circumference is the perimeter of a circle. It is a length and so is measured in \(mm\), \(cm\), \(m\) or \(km\). An area is measured in square units: \(mm^{2 ...

So, the planimeter isn’t just measuring the length of the perimeter, but the size of the perimeter. The final measurement is output in square inches.