Find the curved surface area and total surface area of a cylinder,

Question:

Find the curved surface area and total surface area of a cylinder, the diameter of whose base is 7 cm and height is 60 cm.

Solution:

Let $r$ and $h$ be the radius and the height of the cylinder.

Given :

$\mathrm{r}=\frac{7}{2} \mathrm{~cm}$

$\mathrm{~h}=60 \mathrm{~cm}$

Curved surface area of the cylinder $=2 \pi \times \mathrm{r} \times \mathrm{h}$

$=2 \times \frac{22}{7} \times \frac{7}{2} \times 60$

$=22 \times 60=1320 \mathrm{~cm}^{2}$

Total surface area of the cylinder $=2 \pi \times \mathrm{r} \times(\mathrm{r}+\mathrm{h})$

$=2 \times \frac{22}{7} \times \frac{7}{2} \times\left(\frac{7}{2}+60\right)=22 \times \frac{127}{2}=11 \times 127=1397 \mathrm{~cm}^{2}$

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