Question

I only want to know that how to find this cylinder's total surface area

Answer 1

Answer:

(i) Inner curved surface area = 1936 cm²

(ii) Outer curved surface area = 2129.6 cm²

(iii) Total surface area = 4086.72 cm²

Given:

Length of metal pipe (h) = 77 cm

Inner diameter of cross section (r) = 4 cm

Outer diameter of cross section (r') = 4.4 cm

Step-by-step explanation:

$Curved \: surface \: area \: of \: cylinder = 2\pi rh$

$(i) \: Inner \: curved \: surface \: area = 2πrh \\ \\ = 2 \times \frac{22}{7} \times 4 \times 77 \\ \\ = 2 \times 22 \times 4 \times 11 \\ \\ = 44 \times 44 \\ \\ = 1936 {cm}^{2}$

$(ii) \: Outer \: curved \: surface \: area = 2πr'h \\ \\ = 2 \times \frac{22}{7} \times 4.4 \times 77 \\ \\ = 2 \times 22 \times 4.4 \times 11 \\ \\ = 44 \times 48.4 \\ \\ = 2129.6 {cm}^{2}$

$(iii) Total \: surface \: area \: of \: hollow \: cylinder \: is = 2 \pi (r'+r)(h+r'-r) \\ \\ = 2 \times \frac{22}{7} \times (4.4 + 4) \times (77 + 4.4 - 4) \\ \\ = 2 \times \frac{22}{7} \times 8.4 \times 77.4 \\ \\ = 2 \times \frac{22}{7} \times 650.16 \\ \\ = 2 \times 22 \times 92.88 \\ \\ = 4086.72 {cm}^{2}$