If C = 2πr, then r = C/(2π)
Substituting into A = πr²:
A = π(C/(2π))² = C²/(4π)

If A = πr², then r = √(A/π)
Substituting into C = 2πr:
C = 2π√(A/π) = 2√(πA)

These relationships allow us to find any circle measurement if we know just one value. Try changing the radius and watch how both area and circumference change in relation!