Geometryhard · Past Paper
If the ratio of the areas of two circles is 4:9, what is the ratio of their circumferences?
A2:3
B4:9
C16:81
Dsqrt(2):sqrt(3)
✓ Correct Answer: A — 2:3
Ratio of areas = (r1/r2)^2 = 4/9 => r1/r2 = 2/3. Ratio of circumferences = r1/r2 = 2/3.
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