Basic Shape Areas
You'll use these three formulas constantly in your maths lessons, so getting them sorted now will save you loads of time later.
For squares and rectangles, it's dead simple: just multiply the base by the height. A square with 5cm sides? That's 5 × 5 = 25cm². A rectangle that's 8cm by 3cm? That's 8 × 3 = 24cm².
Triangles need a slightly different approach because they're basically half of a rectangle. Take the base, multiply by the perpendicular height, then divide by 2. So a triangle with a 6cm base and 4cm height gives you (6 × 4) ÷ 2 = 12cm².
Quick Tip: Always check you're using the perpendicular height for triangles - it's the line that goes straight down from the top to the base, not the slanted side!



