Perimeter, Area & Volume Essentials

Perimeter is simply the distance around the outside edge of any flat shape. Think of it like walking around the boundary of a football pitch - you're measuring the perimeter! It's always measured in regular units like centimetres (cm), metres $m$, or millimetres (mm).

For different shapes, you've got simple formulas to remember. Rectangles use 2$a + b$ where 'a' and 'b' are the different side lengths. Squares are even easier - just 4a since all sides are equal. Triangles? Just add up all three sides: a + b + c.

Area measures the space inside a 2D shape - imagine how much carpet you'd need to cover a floor. Notice how area units are always squared (cm², m²) because you're measuring in two dimensions. Rectangles use a × b, squares use a², triangles use ½ab, and circles use πr².

Quick Tip: Remember that perimeter goes around whilst area fills inside - this helps you choose the right formula every time!

Volume tells you how much space a 3D object takes up. For liquids, we measure in millilitres (ml) or litres $l$, but for solid objects, we use cubic units like cm³ or m³. The basic formula is height × width × length, which works perfectly for boxes and rectangular shapes.