Question

a metal pipe is 77 cm long the inner diameter of the cross section is 4 cm and the outer diameter is 4.8 cm find the total surface area

Answer 1

Solution:
Length (L) = 77 cm
Inner diameter (d) = 4 cm
Outer diameter (D) = 4.8 cm

Total surface area = πdL + πDL + 2 × {(πD^2)/4 - (πd^2)/4}
= π × 4 × 77 + π × 4.8 × 77 + 2 × {(π×4.8^2)/4 - (π×4^2)/4}
= 967.61 + 1161.13 + 2 × (18.096 - 12.566)
= 2128.74 + 2 × 5.53
= 2139.8 cm^2

Therefore, total surface area of the metal pipe is 2139.8 cm^2