Luas lingkaran 314 cm² . Phi = 3,14 . Tentukan jari jari , diameter , dan keliling lingkaran

r2=314/3,14=100, r=10cm
d=2r=20cm
k=2.3,14.10=62,8cm

L = 314cm^2
phi = 3,14
r= ?
k=?
L = phi X r^2
314cm^2 = 3,14 Xr^2
314cm^2 = 3,14r^2
3,14r^2 = 314cm^2
r^2 = 314cm^2 : 3,14 
      = 100 cm^2
r^2 = 100cm^2
r = akar dari 100
r= 10cm

K = 2 X phi X r
    = 2 X 3,14 X10
    = 62,8 cm

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