Question:
The area of the curved surface of a cone is $60 \mathrm{~m} \mathrm{~cm}^{2}$. If the slant height of the cone be $8 \mathrm{~cm}$, find the radius of the base.
Solution:
It is given that:
Curved surface area (C. S. A) $=60 \pi \mathrm{cm}^{2}$
Slant height of the cone (l) = 8 cm
Radius of the cone(r) = ?
Now we know,
Curved Surface Area (C. S. A) = πrl
$\Rightarrow \pi r l=60 \pi \mathrm{cm}^{2}$
⟹ r * 8 = 60
⟹ r = 7.5 cm
Therefore the radius of the base of the cone is 7.5 cm.