Answers

2016-02-22T18:23:45+05:30
CSA OF BIGGEST CYLINDER - AREA OF SMALLER CYLINDER
INNER CYLINDER'S RADIUS IS 25-1=24.
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I mean CSA of smallest cylinder
thnx....
The Brainliest Answer!
2016-02-22T18:31:22+05:30
Height of iron pipe = 28 cm

exterior diameter = 25 cm
so the radius is = 25 /2 = 12.5

Thickness of the diameter = 1 cm
so the inner radius = 12.5 - 1 = 11.5 cm

Total surface area of the pipe = Outer curved surface area  + inner curved surface area + area of two bases

2πRh +2πrh + 2 π(R²- r²)

2 × 22/7 × 12.5 × 20 + 2 ×22/7 × 11.5 × 20 + 2 ×22/7 × ( 12.5²-11.5²)

1571.42 + 1445.71+150.85

3197.98 cm² 
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