Oblicz pole koła,ktorego obwod wynosi a)12,56cm b)18,84m

2pir(wzor na obwod)=12,56 //2 stad a. pi r = 6,28 r=6,28/pi wzor na pole pir^2 stad Pole=pi*(6,28/pi)^2 pi*(39,43/pi^2) 39,43pi+pi^3 b. 2pi r=18,84 pi r=9,42 r=9,42/pi pir^2(pole) pi*(9,42/pi)^2 pi*(88,73/pi^2) 88,73pi+pi^3

a) P= πr² 2π=l l=12.56 r= 6.23 p=π * 6.23² = 38.8129πcm² 38.8129 * 3.14 = 121.872506cm² ~ 121.87cm² b) l = 18.84 r = 9.42m p= π * 9.42² = 88.7364πm² 88.7364 * 3.14 = 278.632296 ~ 278.63m²

O=2πr P=πr² a) 12,56=2πr r=6,28 / π P=π(6,28 / π)² P=39,43 / π² P=39,43 / 9,85 ≈ 4cm b) 18,84=2πr r=9,42/π P=π(9,42/π)² P=9,42 / π² P=9,42 / 9,85 ≈ 0,95 m