Lungime a cercului: 2πR
a) 2π3=6π cm;
b) 2π7=14π cm;
c) 2π1,2=2,4π m;
d) 2π2,1=4,2π dm.
RAZA cercului:
π×R²
a) π×3²=9π;
b) π×7²=49π;
c) π×1,2²=1,44π;
d) π×2,1²=4,41π.
