# Circular sheet are each of radius 7 cm and thickness 0.5 cm are placed one above the other to form a right circular cylinder whose total surface area is 1694 cm?.Find the number of circular sheetes required and height

**Solution:**

Let x be the number of sheets placed one above the another to form aright circular cylinder whose total surface area is 1694 sq cm.

Let x be the number of sheets placed one above the another to form a

Then the height of the cylinder is 0.5x

$\therefore Totalsurfacearea=2\mathrm{\pi r}\left(\mathrm{h}+\mathrm{r}\right)\phantom{\rule{0ex}{0ex}}\Rightarrow 1694=2\times \frac{22}{7}\times 7\left(7+0.5\mathrm{x}\right)\phantom{\rule{0ex}{0ex}}\Rightarrow 38.5=7+0.5\mathrm{x}\phantom{\rule{0ex}{0ex}}\Rightarrow 31.5=0.5\mathrm{x}\phantom{\rule{0ex}{0ex}}\Rightarrow \mathrm{x}=63$

Thus 63 sheets were used to form the right circular cylinder.

Height of cylinder = 31.5 cm

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