Tolong di jawab.. #15 poin

Tolong di jawab.. #15 poin

Nomor 1.
$a). : : 2pi.r = 2 times frac{22}{7} times 7 = 44 cm\ b). : : 2pi . r = 2 times frac{22}{7} times 10.5 = 66cm$
Nomor 2.
$a). : pi.d = frac{22}{7} times 2.8 = 8.8cm \ b).pi.d = frac{22}{7} times 35 = 110cm$
Nomor 3.
$a).pi. {r}^{2} = 3.14 times {8}^{2} = 3.14 times 64 = 200.96cm \ b).pi. {r}^{2} = 3.14 times {15}^{2} = 3.14 times 225 = 706.5cm$
Nomor 4.
$a). frac{1}{4} .pi. {d}^{2} = frac{1}{4} times frac{22}{7} times {7}^{2} = 38.5 cm\ b). frac{1}{4} .pi. {d}^{2} = frac{1}{4} times frac{22}{7} times {28}^{2} = 616cm$
Smoga bermanfaat