Question

The total surface area of the cylinder is $1884c{m}^2$ and the height of the cylinder is equal to the diameter of the cylinder. Find the radius (in cm) of the cylinder.$\left(\pi =3.14\right)$

Answer 1

Diameter$=2r$ = height $=h$

$2r=h---------\left(i\right)$

Total surface Area $=2\pi rh+2\pi r^2$

put $h=2r$

$1880=4\pi r^2+2\pi r^2$

$r^2=\frac{1880}{6\pi }$

$=\frac{1880\times 7}{6\times 22}$

$r^2=9.98cm$

$r\simeq 10cm$