Question

From a sheet of 8 sq.m, a closed cylindrical tank is formed which has 1m height and 140 cm diameter.How much sheet will be left after making tank?​

Answer 1

Height of closed cylindrical tank ,h=1 m

Base diameter of cylindrical tank =d=140 cm 

=140/100

=1.4 m

⇒ Radius of cylindrical tank ,r

=d/2

=1.4/2

=0.7 m

Total surface area of cylindrical tank 

=2πr(r+h)=2×22/7×0.7(0.7+1)

=2×22/7×0.7×1.7

=7.48 m^2

so , total 7.48 m^2 sheet is required.

Hope it helps!