Geometry and TrigonometryVery hardRadius where circumference and area match numerically
Geometry and Trigonometry practice question
For a certain circle, the number of units in its circumference equals the number of square units in its area. What is the radius of the circle?
Answer: 2
2πr = πr² gives r = 2.
Common wrong answers
- If you answered 1
- 1 gives circumference 2π and area π.
- If you answered 4
- 4 gives 8π and 16π.
- If you answered 3.14
- 3.14 confuses the radius with π.
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