Question

please help me in mathem.atics​

Answer 1

$circumference = 2\pi \: r$

1. 7cm: 2×22/7×7=44cm
2. 6.3 cm:2×22/7×6.3=39.6
3. 5.6 cm:2×22/7×5.6=35.2 cm
4. 4.2 cm:2×22/7×4.2=26.4 cm