Geometry Basics: Calculating Area, Perimeter, and Volume

Geometry is one of those topics where good visualisation makes all the difference. Always draw a sketch!

Area Formulas — The Top 5

Rectangle: A = l × w. Square: A = s². Triangle: A = (b × h) / 2. Parallelogram: A = b × h. Circle: A = π × r².

Perimeter Formulas

Rectangle: P = 2l + 2w. Square: P = 4s. Triangle: P = a + b + c. Circle: C = 2 × π × r.

Volume Formulas

Cuboid: V = l × w × h. Cube: V = s³. Cylinder: V = π × r² × h. Sphere: V = (4/3) × π × r³.

Pythagoras' Theorem

In every right-angled triangle: a² + b² = c² (c = hypotenuse).

*Example: a = 3 cm, b = 4 cm. c² = 9 + 16 = 25. c = 5 cm.*

Common Mistakes

Confusing radius and diameter! The radius is half the diameter. Forgetting units: cm² for areas, cm³ for volumes.