Tolong bantu jawab dengan caranya

6.
L kubus = 6×8×8 = 384 cm(persegi)
L prisma = L alas + 4×segitiga
= 8× 8 +( 4×1/2×8×tinggi)
tinggi = 3×3 + 4× 4
= 9 + 16
=√(25
= 5
L prisma = 64 + (4×1/2×8×5)
= 64 + 80
= 146 cm

L permukaan = L kubus + L prisma
= 384 + 146
= 530 cm

volume = 8×8×8 + 1/3×8×8×3
= 512 + 64
= 576 cm

6.
Untuk mencari sisi tegak pada Limas kita gunakan pythagoras.

t Limas = 11 - 8 = 3 cm

s² = (r/2)² + t²
s² = (8/2)² + 3²
s² = 16 + 9
s² = 25
s = √25
s = 5 cm

L permukaan = (5 × r × r) + (4 × 1/2 × r × s)
= (5 × 8 × 8) cm² + (4 × 1/2 × 8 × 5) cm²
= 320 cm² + 80 cm²
= 400 cm²

V seluruh = (r × r × r) + (1/3 × r × r × t limas)
= (8 × 8 × 8) cm³ + (1/3 × 8 × 8 × 3) cm³
= 512 cm³ + 64 cm³
= 578 cm³

7.
rusuk Limas = 8 cm

d² = r² + r²
d² = 8² + 8²
d² = 64 + 64
d² = 128
d = √128
d = 8√2 cm

t² = r² - (d/2)²
t² = 8² - (8√2 /2)²
t² = 8² - (4√2)²
t² = 64 - 32
t² = 32
t = √32
t = 4√2 cm

V oktahedron = 2 × 1/3 × r × r × t
= 2 × 1/3 × 8 × 8 × 4√2 cm³
= 512√2 /3 cm³