L = ¾ x π x r²
d = 14 cm, r = 7 cm
K = ¾ x 22/7 x 14 + 2 x 7
= 3/2 x 11 x 2 + 14
= 3 x 11 + 14
= 47 cm
L = ¾ x 22/7 x 7²
L = 3/2 x 11 x 7
L = 231/2 = 115, 5 cm²
3. Diketahui : diameter = tinggi tabung = 20 cm
V = luas alas x tinggi tabung
V = π x r² x t
V = 3,14 x 10 x 10 x 20
V = 314/100 x 100 x 20
V = 314 x 20
V = 6.280 cm³
L = 2 x alas + selimut tabung
L = 2 x π x r² + π x d x t
L = 2 x 314/100 x 100 + 314 /100 x 20 x 20
L = 628 + 1256
L = 1.884 cm²
4. L = luas permukaan kubus + luas permukaan limas
Luas kubus = 6 x s2 = 6 x 82 = 384.
Luas sisi tegak limas = luas alas + (4 x luas tegak segitiga) = s x s + (4 x 8)
= 8 x 8 + 32 = 96
Luas bangun adalah 384 + 96 = 480