19.3 Arc length and sector area — Practise

1. A sector has radius 6 cm and angle 60°. Work out its arc length in terms of π.
2. A sector has radius 9 cm and angle 120°. Work out its arc length in terms of π.
3. A sector has radius 4 cm and angle 90°. Work out its area in terms of π.
4. A sector has radius 6 cm and angle 150°. Work out its area in terms of π.
5. A sector has radius 3 cm and angle 120°. Work out its perimeter in terms of π.
6. A sector is one quarter of a circle with radius 8 cm. Work out its area in terms of π.
7. An arc of a circle with radius 12 cm subtends 60°. Work out its length in terms of π.
8. A sector has area 20π cm² in a circle of radius 10 cm. Work out its angle.