tlg ya. no 28 & 29. thnkyouu

29 .V = V1 + V2
= ( 1/2 x a x t x tp) + ( P x l x t )
= ( 1/2 x 10 cm x 8 cm x 18 cm ) + (18 cm x 10 cm x 12 cm )
= 720 cm + 2160 cm
= 2.880 cm

(28.)
diketahui:
p balok = 18 cm
l balok = 10 cm
t balok = 12

p prisma = 18 cm
l prisma = 10 cm
t priama = 20 - 12 = 8 cm

ditanya : v = ....?
jawab
v balok = p x l x t
v balok = 18 x 10 x 12
v balok = 2160 cm³

v prisma = luas alas segi tiga x panjang
v prisma = (1/2 x 10 x 12) x 18
v prisma = 60 x 18
v prisma = 1080 cm³

v balok + v prisma = 2160 + 1080 = 3240 cm³

(29)
diketahui
p prisma = l prisma = 10 cm
t prisma = 6 cm

p limas = p prisma = l prisma = 10 cm
t limas = 12 cm

ditanya : luas permukaan bangun

jawab
a. luas permukaan prisma
LP prisma = L 4 x dinding + L alas
LP prisma = 4 x p x t + p x l
LP prisma = 4 x 10 x 6 + 10 x 10
LP prisma = 240 + 100
LP prisma = 340 cm²

b. luas permukaan limas
(t segitiga limas)² = (1/2 p)² + (t limas)²
(tsegitiga limas)² = (1/2 x 10)² + 12²
(t segitiga limas)² = 5² + 12²
(t segitiga limas)² = 25 + 144
t degitiga limas = √169
t segitiga limas = 13 cm

LP limas = 4 x dinding segitiga
LP limas = 4 x (1/2 x p x t segitiga)
LP limas = 4 x (1/2 x 10 x 13)
LP limas = 4 x ( 65 )
LP limas = 260 cm²

jadi,
LP prisma + LP limas = 340 + 260 = 600 cm²