Geometry and TrigonometryMediumRadius from an arc length and its central angle
Geometry and Trigonometry practice question
In a circle, a central angle of 45° cuts off an arc of length 3π. What is the radius of the circle?
Answer: 12
45° is one eighth of the circle, so the circumference is 8 × 3π = 24π and the radius is 12.
Common wrong answers
- If you answered 3
- 3 copies the arc's coefficient.
- If you answered 6
- 6 uses a quarter instead of an eighth.
- If you answered 24
- 24 is the diameter.
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