Geometry — Quadrilaterals and Circles
| Shape | Area | Perimeter |
|---|---|---|
| Rectangle | l × w | 2(l + w) |
| Square | s² | 4s |
| Parallelogram | base × height | 2(l + w) |
| Trapezoid | ½(b₁ + b₂) × h | sum of sides |
Circle: - Circumference: C = 2πr = πd - Area: A = πr² - π ≈ 3.14159 (often use 3.14 or 22/7) - Diameter = 2 × radius