The external diameter of an iron pipe is 20 cm audits length is 12 cm. If the thickness of the pipe is 1 cm. find the surface area of the pipe (take π = $\frac{22}{7}$) correct to two places of decimal.

1,552.57 cm²

We know that,

Curved surface of a cylinder = 2πrh

Area of a circle = πR² 

We have,

The external diameter of an iron pipe = 20 cm

Length = 12 cm. 

Thickness = 1 cm.

External radius of the iron pipe, R = \(\frac{20}{2}\) = 10 cm

Internal radius of the iron pipe, r = 10 - 1 = 9 cm

Height, h = 12 cm

​According to the concept = Total surface area of the pipe = Outside surface area + inside surface area + Top Base Area + bottom base area

2πRh + 2πrh + π(R²−r²) + π(R²−r²)

= 2πh(R + r) + 2π(R²−r²)

= 2π {12 × (10 + 9) + (10² - 9²)}  = 1,552.57 cm²