f. Luas = (2Ꙥ x 3,5 x 3,5) + (2Ꙥ x 3,5 x 20)
= 24,5Ꙥ + 140Ꙥ
= 164,5Ꙥ cm²
Volume = Ꙥ x 3,5 x 3,5 x 20
= 245Ꙥ cm³
Kunci Jawaban Matematika kelas 9 halaman 281
2. Tentukan panjang dari unsur tabung yang ditanyakan.
Jawab:
a. V = Ꙥ x r x r x t
600Ꙥ = Ꙥ x 10 x 10 x t
t = 600Ꙥ / 100Ꙥ
t = 6 cm
b) L = 2Ꙥ x r x (r + t)
120Ꙥ = 2Ꙥ x 5 x (5 + t)
5 + t = 120Ꙥ / 10Ꙥ
5 + t = 12
t = 7 cm
c) V = Ꙥ x r x r x t
224Ꙥ = Ꙥ x 4 x 4 x t
t = 224Ꙥ / 16Ꙥ
t = 14 cm
d) L = 2Ꙥ x r x (r + t)
528Ꙥ = 2Ꙥ x r x (r + 13)
528Ꙥ = 2Ꙥ x r² + 13r
r² + 13r - 264 = 0
(r + 24) (r - 11)
r = 11 cm
e) L = 2Ꙥ x r x (r + t)
450Ꙥ = 2Ꙥ x r x (r + 15)
450Ꙥ = 2Ꙥ x r² + 15r
r² + 15r - 225 = 0
r = 9 cm