Tolong bantuannya kakak²​

38. 7 cm (D)

39. 616 cm² (A)

No. 38

Diketahui

• V = 770 cm³

• t = 15 cm

• π = 22/7

Ditanya

• r

No. 39

Diketahui

• d = 14 cm

• r = 7 cm

• π = 22/7

Ditanya

• Lp

JAWAB

No. 38

• V = ⅓πr²t

• 770 = ⅓ × 22/7 × r² × 15

• 154 = ⅓ × 22/7 × r² × 3

• 154 = 22/7 × r²

• 22r² = 154 × 7

• 22r² = 1.078

• r² = 1.078/22

• r² = 49

• r = 7 cm => (D)

No. 39

• Lp = 4πr²

• Lp = 4 × 22/7 × 7²

• Lp = 4 = 22 × 7

• Lp = 616 cm² => (A)