(A) Cube with side = 6 cm
Surface area of cube = 6 × (side)²
Surface area = 6 × 6²
=6×36
=216 cm²
(B) Cylinder with diameter = 14 cm, height = 80 cm
Total surface area = 2πr(r + h)
Radius (r) = 14 ÷ 2 = 7 cm
Height (h) = 80 cm
Using π = 22/7:
Surface area = 2 × (22/7) × 7 × (7 + 80)
=2×22×87
=44×87
=3,828 cm²
(C) Cone with diameter = 14 cm, slant height = 10 cm
Total surface area = πr(r + l)
Radius (r) = 14 ÷ 2 = 7 cm
Slant height (l) = 10 cm
Using π = 22/7:
Surface area = (22/7) × 7 × (7 + 10)
=22×17
=374 cm²
(D) Sphere with radius = 10.5 cm
Surface area = 4πr²
Radius = 10.5 cm = 21/2 cm
r² = (10.5)² = 110.25
Using π = 22/7:
Surface area = 4 × (22/7) × 110.25
=4×722×4441
=22×63
=1,386 cm²
Comparing surface areas:
(B) Cylinder: 3,828 cm²
(D) Sphere: 1,386 cm²
(C) Cone: 374 cm²
(A) Cube: 216 cm²
Decreasing order: (B), (D), (C), (A)