CIR016 · Circles · Classes 8–12
Sector
A “pizza slice” of a circle between two radii and an arc.
Sector📐 Formula
Area = (θ/360°) × πr² = ½r²θ (θ in radians); Arc length = (θ/360°) × 2πr
✏️ Worked example
r = 6, θ = 60°: area = 6π ≈ 18.85, arc ≈ 6.28.
🌍 Where it is used
Pie charts, fans and slices of food.
❓ Quick check
A sector with θ = 90° is what fraction of the circle?