Question

solve this word problem

Answer 1

Answer:

Length of the pipe = 21 cm

External diameter = 25 cm

External radius, R = 12.5 cm

Thickness of the pipe, w = 1 cm

Internal radius = 12.5 – 1 = 11.5 cm

Area of the pipe = outer area – inner area

Outer area = 2πr(r + h)

                 = 2π×12.5(12.5 + 21)

                 = 2π×12.5×33.5

                 = (837.5)π cm²

Inner area = 2πr(r + h)

                = 2π×11.5(11.5 + 21)

                 = 2π×11.5×33.5

                = (747.5)π  cm²

Hence surface area of the pipe = (837.5)π – (747.5)π

                                    = 90π

                                    = 90 × 3.14

                                    = 282.6 cm²

∴ Surface area of the pipe = 282.6 cm²

Step-by-step explanation: