TOLONG DI JAWAB SAYA BESOK UN

Bab Bangun Ruang
Matematika SMP Kelas VIII

12] prisma alas belah ketupat
s = √((1/2 x d1)² + (1/2 x d2)²)
s = √((1/2 x 12)² + (1/2 x 16)²)
s = √(36 + 64)
s = 10

luas permukaan
= (2 x 1/2 x d1 x d2) + (4s x t)
= (12 x 16) + (4 x 10 x 20)
= 192 + 800
= 992 cm²

◎◎ B ◎◎

13] kerucut
luas selimut = π x r x s = 188,4
3,14 x r x 10 = 188,4
r = 188,4 : 31,4
r = 6 cm

t = √(s² - r²)
t = √(10² - 6²)
t = √(100 - 36)
t = 8 cm

volume = 1/3 x π x r² x t
volume = 1/3 x 3,14 x 6 x 6 x 8
volume = 301,44 cm kubik

◎◎ C ◎◎