Geometry and TrigonometryMediumArea of a sector
Geometry and Trigonometry practice question
A circle has a radius of 6. What is the area of a sector with a central angle of 60°?
- A. 2π
- B. 6πCorrect
- C. 12π
- D. 36π
Answer: B. 6π
A 60° angle is 60/360 = 1/6 of the circle. The full area is π(6²) = 36π, so the sector is (1/6)(36π) = 6π. Choice A (2π) is the arc length of that sector, not its area.
Why the other answers are wrong
- A. 2π
- 2π is the arc length of the 60° sector, not its area. Take 1/6 of the full area 36π to get 6π.
- C. 12π
- 12π is the full circumference of the circle (2π · 6), not a sector area. Use area: (1/6)(π · 6²) = 6π.
- D. 36π
- 36π is the area of the entire circle. A 60° sector is only 60/360 = 1/6 of that, so the answer is 6π.
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