Odpowiedź:
L = 2πr
P = πr²
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r = 4,5
L = 2π * 4.5 = 9π
P = π * 4.5² = 20,25π
L = 18π / :2π
r = 9
P = π * 9² = 81π
P = 16π / √
P = 4π / :π
r = 4
L = 2π * 4 = 8π
