Geometryhard · Past Paper
If the area of a circle is A, and its circumference is C, then which of the following is true?
AC^2 = 4*pi*A
BC^2 = pi*A
CA = 2*pi*C
DC = 4*pi*A^2
✓ Correct Answer: A — C^2 = 4*pi*A
C = 2*pi*r, C^2 = 4*pi^2*r^2. A = pi*r^2. So C^2 = 4*pi*A.
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