1. Problem 9: The hour hand on a clock is 12 cm long. What area does it pass over in 5 h? Take π as 3.14. 2. Formula: Area of sector = $$\frac{\theta}{360} \times \pi r^2$$ where $\theta$ is the angle in degrees and $r$ is the radius. 3. The hour hand moves 360° in 12 hours, so in 5 hours it moves $$\frac{5}{12} \times 360 = 150^\circ$$. 4. Calculate area: $$\text{Area} = \frac{150}{360} \times 3.14 \times 12^2 = \frac{150}{360} \times 3.14 \times 144$$ 5. Simplify fraction: $$\frac{150}{360} = \frac{\cancel{150}}{\cancel{360}} = \frac{5}{12}$$ 6. Calculate area: $$\text{Area} = \frac{5}{12} \times 3.14 \times 144 = \frac{5}{12} \times 452.16 = 188.4$$ 7. Final answer: The area passed over is approximately 188.4 cm². 1. Problem 12: Sector of a circle with radius 35 m and central angle 120°. 2. Find the area of the sector. 3. Use formula: $$\text{Area} = \frac{120}{360} \times \pi \times 35^2 = \frac{1}{3} \times \pi \times 1225$$ 4. Calculate area: $$\text{Area} = \frac{1}{3} \times \frac{22}{7} \times 1225 = \frac{1}{3} \times 3850 = 1283.33$$ 5. Final answer: Area of sector is approximately 1283.33 m². 1. Problem 14: Sector with radius 7 cm and central angle 120°. (a) Perimeter of sector = arc length + 2 × radius. (b) Area of sector = $$\frac{\theta}{360} \times \pi r^2$$. 2. Calculate arc length: $$\text{Arc length} = \frac{120}{360} \times 2 \times 3.142 \times 7 = \frac{1}{3} \times 2 \times 3.142 \times 7 = 14.66$$ cm 3. Calculate perimeter: $$\text{Perimeter} = 14.66 + 2 \times 7 = 14.66 + 14 = 28.66$$ cm 4. Calculate area: $$\text{Area} = \frac{120}{360} \times 3.142 \times 7^2 = \frac{1}{3} \times 3.142 \times 49 = 51.3$$ cm² 5. Final answers: (a) Perimeter = 28.66 cm (b) Area = 51.3 cm² 1. Problem 16: Not provided in user message, skipping as per instructions. 1. Problem 20: Not provided in user message, skipping as per instructions.