Jawaban:

5. D. 1.200 cm²

6. B. 288 cm²

7. C. 1088 cm²

Penjelasan dengan langkah-langkah:

5.L= 2×(pl + lt + pt)

L= 2×(18×15 + 15×10 + 18×10)

L= 2×(270 + 150 +180)

L= 2×(600)

L= 1.200 cm²

6. s√3 = 12

s = 12/√3 cm

Luas permukaan = 6.s.s

= 6.12/√3.12/√3

= 288 cm²

7.V.balok = plt

1.536 = 6y × 4y × 1y

1.536 = 24 y^3

y^3 = 1.536/24

y^3 = 64

y = 4

maka, diketahui :

p = 6y = 6(4) = 24

l = 4y = 4(4) = 16

t = y = 4

Luas permukaan :

2(pl + lt + pt) = 2×(24×16 + 16×4× + 24×4)

= 2×(384 + 64 + 96)

= 2×(544)

= 1.088 cm²

semoga membantu ya :)