Question

Form a sheet of $8$ square meter, a closed cylindrical tank is formed which has one meter height and $140cm$ diameter. How much sheet will be left after making tank?

Answer 1

Sheet left = Area of sheet - surface are of cylinder

$=8m^2-(2\pi r^2+2\pi rh)$

$8m^2-2\pi r(r+h)$

$8-2\times \frac{22}{7}\times \frac{140}{2\times 100}(\frac{140}{2\times 100}+1)$

$=8-2\times \frac{22}{7}\times \frac{140}{2\times 100}\times 1.7$

$=8-7.48m^2$

$=0.52m^2$