Question

A metal pipe has exterior diameter25cm and it is 1cm thick. Find the whole surface area of the pipe if it is 21cm long

Answer 1

Answer:

Solution:

Height of pipe = 21 cm External diameter = 25 cm

External radius = 25/2 = 12.5 cm

Internal diameter = 25 - (1 + 1)

= = 24 cm

Internal radius = 24/2 = 12 cm

Let the external radius be R and the internal radius be r.

=

Total surface area of the pipe = 2Th(R

+ r) + 2n(R? - r2) 2*22/7*21(12.5 + 12) + 2*22/7*(12.5)?

- (11.52) → (44*480)/7 + (44*24)/7

21120/7 + 1056/7

22176/7 = - 3168 cm2

So, the total surface area of the pipe is

3168 square cm.

Answer 2

Answer:

Given

Height of pipe = 21 cm

External diameter = 25 cm

External radius = 25/2 = 12.5 cm

Internal diameter = 25 - (1 + 1)

= 23 cm

Internal radius = 23/2 = 11.5 cm

solution

Let the external radius be R and the internal radius be r.

Total surface area of the pipe = 2πh(R + r) + 2π(R² - r²)

⇒ 2× 22/7 × 21(12.5+11.5) +2×22/7(12.5)^2-(11.5)^2

=> 1530 + 150.85

So, the total surface area of the pipe is 1680.85 square cm.

Step-by-step explanation:

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