Question

Question 2
Write ‘True’ or ‘False’ and justify your answer in the following :
A solid cylinder of radius r and height h is placed over other cylinder of same height and radius. The total surface area of the shape so formed is $4\pi rh+4\pi r^2$.

Answer 1

This statement is false.
Since, the total surface area of cylinder of radius, r and height ,
$h=2\pi rh+2\pi r^2$
When one cylinder is placed over the other cylinder of same height and radius.
Then height of the new cylinder = 2h
And radius of the new cylinder = r
$\therefore$ Total surface area of the new cylinder $=2\pi \left(2h\right)+2\pi r^2=4\pi rh+2\pi r^2$