Question

An iron pipe 20 cm long has exterior diameter equal to 14 cm. If the thickness of the pipe is 1 cm, then the whole surface of the pipe is​
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Answer 1

Explanation:

Height=20 cm

exterior diameter= 14cm

Therefore, exterior radius(R)=14/2=7.

Thickness of Pipe= 1cm.

Therefore Inner Radius (r)=R - Thickness

7-1=6

Assuming that top and bottom are open, Whole surface area of Pipe=

2πh(R+r) + 2π (R^2-r^2)

2 x 22/7 (7+6) + 2 x 22/7 (7^2-6^2)

=44/7 x 13 + 44/7 x 13

=81.71 x2

=163.428

my answer is correct....if m wrong tell me in comments