Question

The surface area of a solid cylinder of radius 2.0 cm and height 10.0 cm is equal to ______ (mm)².

Answer 1

The surface area of a solid cylinder of radius 2.0 cm and height 10.0 cm is equal to 1.5 × 10⁴ (mm)².

Explanation:

The total surface area of a cylinder of radius r and height h is

S = 2πr (r + h).

Given that,

r = 2 cm = 2 × 1 cm = 2 × 10 mm = 20 mm

h = 10 cm = 10 × 10 mm = 100 mm

∴ S = 2 x 3.14 x 20 x (20+100) = 15072 mm² = 1.5 × 10⁴ mm²

Answer 2

Surface area = 2πrh + 2πr² = 2πr (h + r)

= `2 xx 22/7 xx 2 xx 10 (10 xx 10 + 2 xx 10)` mm² 

= 1.5 x 10⁴ mm² Hence, answer is 1.5 x 10⁴.