tolong jawab yaaa pakai cara

1. c

2. b
r = √v /(pi*t) = √ 6280/ ( 3,14 * 20 ) = √ 6280 / 62,8 = √100 = 10 cm

3. c
luas selimut = k * t = 2 * pi * r * t = 2 * 3,14 * 10 * 20 = 1.256 cm'2
2 luas lingkaran = 2 * pi * r * r = 2 * 3,14 * 10 * 10 = 628 cm'2
luas permukaan tabung = 1.884 cm'2