CIR020 · Circles · Classes 8–11
Pi approximation
Archimedes trapped π between the perimeters of polygons drawn inside and outside a circle of diameter 1. More sides squeeze the bounds together. Aryabhata gave π ≈ 3.1416.
π ≈ 3.14Pi approximation
📐 Formula
n sin(π/n) < π < n tan(π/n)
✏️ Worked example
Hexagons: 3 < π < 3.46. With 96 sides: 3.1410 < π < 3.1427.
🌍 Where it is used
How π was calculated before computers.
❓ Quick check
Which is closest to π?
🏋️ Practice
EasyAryabhata's value: 62832/20000 = ?
Answer: 3.1416
MediumIs 22/7 exactly π?
Answer: No (22/7 ≈ 3.1429)
ChallengeDo the bounds get closer with more sides?
Answer: Yes