Example 1 · level 1
A sector of a circle of radius 14 cm has angle 135°. Find the area of the sector (in cm²), to 2 decimal places if needed. Use π = 22/7.
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- Area = 135/360 × 22/7 × 14² = 231 cm².
Answer: 231
CLASS 10 MATHS · AREAS RELATED TO CIRCLES
Area of a sector and length of an arc
Sector area = (θ/360) × πr². Arc length = (θ/360) × 2πr. Use π = 22/7.
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Worked examples
Example 2 · level 2
A sector of a circle of radius 14 cm has angle 180°. Find the area of the sector (in cm²), to 2 decimal places if needed. Use π = 22/7.
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- Area = 180/360 × 22/7 × 14² = 308 cm².
Answer: 308
Example 3 · level 3
The minute hand of a clock in a Ranchi railway station is 7 cm long. What area does it sweep in 30 minutes (in cm², to 2 decimal places if needed)? Use π = 22/7.
Show solution
- θ = 30 × 6° = 180°.
- Area = 180/360 × 22/7 × 49 = 77 cm².
Answer: 77